Exactly a year ago — August 10 2015 — Xiaomi announced the Redmi 2 Prime. This was the upgraded, Made in India version of its most popular budget smartphone.The new Redmi 3S Prime is the spiritual successor to that phone — created with the specific intention of bringing better design and higher quality hardware to the budget segment. This too, proudly wears the Made in India tag from day 1 — indicative of the sheer numbers that the company is hoping to achieve with this phone.There are actually two versions of the phone — Redmi 3S Prime and the Redmi 3S (the lower spec and cheaper 3S does without a fingerprint scanner and has half the RAM, half the storage — but the same basic design).In terms of design, the Redmi 3S and 3S Prime look and feel like shrunken down versions of the Redmi Note 3 — which is a good thing. We love the premium look and feel of the Redmi Note 3 and the Redmi 3S/Redmi 3S Prime offer much of the same at a lower price — in a smaller, easier-to-hold, form factor.Both phones have a similar style metal unibody design, curved back, fingerprint scanner (not available on Redmi 3S) on the back, a 1mm nub above the rear speaker to lift it off flat surfaces for better audibility and similar speaker grills.However, the camera is placed on the left top corner like the Mi 4i (the Redmi Note 3 has it in the center). On the right side are the power button and volume keys while the left has the hybrid SIM slot. Battery life is something that Xiaomi is paying special attention to — inside this phone is a 4,100mAh battery — it’s actually a tad larger than the battery on the Redmi Note 3.Thanks to the large battery and metal design, the phone is heavy at 144 grams but it does not feel bulky and the weight is evenly distributed. Two thumbs up to Xiaomi for delivering a premium metal design in a compact size on a budget.Up front is a 5-inch IPS display with a resolution of 1280 x 720 pixels. We were impressed by the slim bezels around the screen as well as the brightness, colour reproduction and viewing angles. Like the Redmi 2, the Redmi 3S also skips the backlight on the navigation buttons under the display which is a disappointment. Performance is an area where the Redmi 3S beats most if not all the competition in this price range.This is the first smartphone with the new octa-core Qualcomm Snapdragon 430 processor. The cheaper Redmi 3S comes with 2GB RAM/16GB storage while the Redmi 3S Prime has 3GB RAM with 32GB storage. Our review unit of the Redmi 3S Prime with 3GB RAM and 32GB storage had no issues playing games such as Dead Trigger 2, N.O.V.A and Asphalt Nitro.It was only when there was a heavy game running in the background and we played another one that we noticed there were some random frame drops during gameplay. We faced no issues playing full HD videos (using MX player), switching between background apps and there was no heating issue as well.The IR blaster is placed on the top and works well with the pre-loaded Mi remote app. With the new processor, 720p screen and large battery — you get fantastic battery life.On most days, the Redmi 3S Prime managed to deliver over a day and a half battery life. Even with heavy use, the phone will last from 9am to 9pm with some to spare. Although there is no QuickCharge, it does charge fairly fast with the supplied 10W (5V, 2Amp) charger.It goes from 0 to 50 per cent in just over an hour. Because of the large battery, charging the phone from 0 to 100 per cent usually takes about 3 hours. On most budget smartphones, the camera is usually the weakest link. Much to our surprise, that is not the case with the Redmi 3S Prime.The phone has a 13MP primary camera with phase detection autofocus and f2.0 aperture. The 5MP front camera has an aperture of f2.2. In the real world, the phone manages to take great photos in daylight from both cameras. Auto focus and shutter speed are also impressively fast — you tap the shutter button and the image is saved with the camera ready for the next.However, indoor photos have visible noise in dark areas while in low-light the level of visible noise increases — these photos are still good enough to view on the phone.Out of the box, the phone comes with MiUI 7 based on Android 6.0. We have always loved MiUI for its unique feature set including a built-in virus scanner, one hand mode, lite mode, Mi cloud sync, junk cleaner, data monitor, theme support, permissions manager and plenty of customization options.However, you do get a set of pre-loaded bloatware apps on the phone now. This includes Flipkart, Amazon Shopping, Kindle, WPS Office and Facebook. Xiaomi says that MiUI 8 for the Redmi 3S will be available soon (end of August) — MiUI 8 adds a number of new features on the phone.Having spent over a week with the phone, it’s clear that the Redmi 3S is another game change from Xiaomi in the sub-Rs 10,000 bracket. It’s sturdy, looks great, offers excellent performance, above average camera quality and stellar battery life.Probably the only issue is that the Redmi 3S Prime is priced too close to the 2GB version of the Redmi Note 3 (Rs 9,999). Redmi Note 3 has a full HD display, faster processor and battery life that is almost as good.