Xiaomi's new Redmi 4 borrows heavily from last year's Redmi 3S (Prime) in almost all the major departments, and yet, when you look at it for the first time and take it out for a ride, it's a whole new ball game altogether. It's about refining the jagged edges of the original classic, a trait only the best in the business could fathom.

Xiaomi already had a pretty fantastic phone in the Redmi 3S (Prime) after all. No wonder, it sold over 40 lakh units of the phone in India in just 9 months. There was only so much that it could add to its successor to warrant an upgrade. Take a look.

Design and build quality

The Redmi 4 looks a lot like the Redmi Note 4. Only smaller. Straight off the bat, the Redmi 4 is for someone who prefers a smaller phone. A 5-inch one to be precise. Because it borrows heavily from the Redmi Note 4's design aesthetics, the Redmi 4 invariably shares both its upsides and downsides in equal measure.

Also Read: Xiaomi Redmi 4 4GB RAM, 64GB memory variant won't be available until June end

It's a looker, the Redmi 4. There are absolutely no two ways about it. Just like the Redmi Note 4, the Redmi 4 also comes in a matte black finish (and gold) that gives it a premium, upmarket look and feel clearly defying its ultra-affordable price tag. It looks like an expensive phone, that isn't expensive at all.

The Redmi 3S Prime came with a full-metal body: a first for any smartphone in and around its product category. With the Redmi 4, Xiaomi has added curved 2.5D glass with rounded edges and polished antenna lines, into the mix. Xiaomi has stuck with the good old 'if it ain't broke, don't fix it' formula here. Which is nice because there wasn't much to complain about the Redmi 3S Prime's design anyways. At the same time, additions like the curved 2.5D glass and bottom-firing mono speaker vent ensure the Redmi 4 doesn't end up looking like a recycled Redmi 3S Prime.

Just like the Redmi 3S Prime, the Redmi 4 crams in a massive 4,100mAh battery inside, and just like the Redmi 3S Prime, the Redmi 4 also feels practically the same no matter how you hold it. An all-metal build comes at a price though. Things are bound to get a little slippery every now and then. But while in the case of the Redmi 3S, a chrome strip on the front (and chamfers) helped a great deal in balancing the equation and enhancing the grip, the Redmi 4 -- because it's a lot curvier in comparison -- isn't the most ergonomic all-metal smartphone (at its price point) like its predecessor was back in the day. The Redmi 3S Prime is still pretty much the King in the North in this regard.

The Redmi 4 is all about refining the jagged edges of the Redmi 3S, a trait only the best in the business could fathom

Moving on, the Redmi 4 -- just like the Redmi 3S -- has an always-on fingerprint scanner on the back (which works well most of the time unless you have greasy or sweaty fingers) and physical capacitive keys on the front which are (still) not backlit. The power button and the volume rocker are on the right, while the dual-SIM hybrid card slot lies on the left. All in all, the Redmi 4 is a well-made smartphone that screams premium from every nook and corner, just like its predecessor. If anything, it's even better looking than the Redmi 3S Prime.

Display

The Redmi 4, like the Redmi 3S Prime, comes with a 5-inch 720p IPS LCD display. Brightness levels are just about adequate and adaptive brightness works as it should. Colours look rich and vibrant -- a little warm by default -- but there's a manual correcting mode inside that helps achieve better results, albeit only slightly. There's also an in-built reading mode that turns colours to the warmer end of the spectrum for night-time reading.

The Redmi 4, like the Redmi 3S Prime, also misses out on Xiaomi's hallmark Sunlight Display technology. This means even though the phone has good enough brightness levels indoors, these go for an all-out toss when you're out in direct sunlight, so do the phone's viewing angles. Despite its somewhat low brightness output, the Xiaomi Redmi 4 still manages to better rival phones around its price category in display department, especially in colour accuracy.

Software

The Redmi 4 runs Android 6.0.1 Marshmallow (based MIUI 8) a two year old operating system at a time when Google is all set to launch Android O. "We will have Android N Preview available out-of-the-box. From our perspective, we don't update a phone just to change an Android version number. But, actually it has to make the phone better," a Xiaomi spokesperson explained to me not long ago. All said and done, Xiaomi still doesn't have a definite timeline for when its phones -- including the Redmi 4 -- will get the Android Nougat update.

Latest software iteration does not necessarily translate to drastic changes in Xiaomi's interface though. There's generally very little difference between a KitKat-based MIUI and a Marshmallow-based MIUI which could be a deal-breaker for stock Android fanatics, even more so because Xiaomi's MIUI kills off key Android 6 interface elements, like Now on Tap.

If, however you are not a "stock Android fanatic", MIUI 8 offers all the bells and whistles that you'd want from a fully-functional operating system, including themes. Some of its features like scrollable screenshots, second space and dual apps are worth mentioning.

Additionally, the Redmi 4 comes with an IR-blaster that can be used (in tandem with the Mi Remote app or even some third-party solutions) to control smart home appliances.

Performance and battery life

The Redmi 4 is powered by a 1.4GHz octa-core Qualcomm Snapdragon 435 processor (a decent upgrade over the Redmi 3S Prime's Snapdragon 430, adding X8 LTE into the mix for faster Cat 7 download/upload speeds) coupled with Adreno 505 GPU and up to 4GB of RAM. It comes with up to 64GB of internal memory which is further expandable by up to 128GB via a micro-SD hybrid card slot. The dual-SIM phone supports 4G LTE (VoLTE-ready) and USB OTG.

Also Read: Xiaomi Redmi 4 quick review: You might actually be able to buy this phone

The Redmi 4 is also quick and responsive in every sense of the word, much like its predecessor phone. There were no visible lags or stutter while navigating between home screens and/or multitasking in our (3GB RAM/32GB memory) review unit. Basic games are handled well, but GPU-intensive games are prone to some occasional lags when being played at maxed out settings for longer periods. Most importantly, just like the Redmi 3S Prime, the Redmi 4 also doesnt heat up at all, even under stress.

The Redmi 4 China version ships with a Snapdragon 625 processor under the hood though, which is, a little disappointing. "The processor is a pretty big component when it comes to the cost of a phone. Using a bigger processor would drive the cost up. You have to see the whole thing as a sum of its parts and because the processor is one of the most expensive components, it's not the case that we can just swap it out. We had a pretty good successful formula with the Redmi 3S, and we wanted to sort of keep things roughly in the same price," the spokesperson said.

The mono speaker on-board the Redmi 4 is average at best. It gets loud but there is often some digitisation observed at peak volume. Voice quality during calls made with the Redmi 4 was excellent.

As opposed to a phone like the Redmi 3S Prime, you might actually be able to buy the Redmi 4 if Xiaomi's claims are to be gone by

The Redmi 4, much like the Redmi 3S Prime, is backed by a 4,100mAh battery and much like the Redmi 3S Prime, the Redmi 4 also offers unbeatable battery life. Moderate to extreme usage saw us cross the one whole day barrier with ease, while toning down further should get most users one and a half days out of the phone. Extreme usage scenarios got us close to 14 hours on the Redmi 4, which is kind of amazing.

The phone, although it supports Qualcomm's Quick Charge, doesn't ship with a fast charger in the box which is, again, disappointing because charging the Redmi 4 really takes a lot of time (over 2 hours) using a standard charger.

Camera

The Redmi 4, much like the Redmi 3S Prime, sports a 13-megapixel camera on the rear with f/2.0 aperture, Phase Detection Autofocus along with an LED flash. On the front you get a 5-megapixel snapper.

Much like the Redmi 3S Prime, the Redmi 4 also captures some good-looking photos in good light with good amount of detail and mostly spot-on (if a little oversaturated) colours. Dynamic range could have been better but then none of the camera phones at under Rs 10,000 have dynamic range to really brag about. They are just about average. The Redmi 4 is a tad better.

Xiaomi's phone is also able to capture well-enough photos in tricky light situations with good detail. Low light photos are prone to noise.

The front-facing selfie camera is just about average with some noise, even in good lighting.

Should you buy it?

Essentially, the Redmi 4 is the Redmi 3S Prime in a fancy new bottle. A Redmi 3S Prime HD remaster, if you may. You're better off if you already own the Redmi 3S Prime. That phone should serve you well, at least for another year or so. For others, well, the Redmi 4 is definitely a recommended buy. Xiaomi will be looking to discontinue the Redmi 3S Prime in the days to come, and in that case, it's safe to say that the Redmi 4 is every bit as awesome as the phone that it will replace. It looks really good, feels really good, has a neat display, dependable performance, good-enough cameras and killer battery life. It's still super cheap to buy as well. The Redmi 4 will be available for buying at a starting price of Rs 6,999 for the 2GB RAM and 16GB memory version going all the way to Rs 10,999 for the top end 4GB RAM and 64GB memory version. The Redmi 4 will also be available in 3GB RAM and 32GB memory version for Rs 8,999.

But more importantly, as opposed to a phone like the Redmi 3S Prime, you might actually be able to buy the Redmi 4 if Xiaomi's claims are to be gone by.

The Redmi 4 comes at a time when Xiaomi is slowly and steadily ramping up its sales strategy in the country. The company recently opened its first Mi Home store in India in Bengaluru to bring its products to offline sales channels. It is also looking to open Mi Home stores in Delhi, Mumbai, Hyderabad, and Chennai in the days to come. In fact, it plans to open as many as 100 Mi Homes in the country in the next two years.

Xiaomi phones, although value for money, are notorious for being out of stock almost all the time. An online-only sales approach also meant it was impossible for people to personally try out these phones before making a purchase. A Mi Home store will solve both the purposes. "We're going to guarantee availability in Mi Home and if we don't have physical stock, we're going to give you an F-code," the spokesperson reiterated.