I’ve been using the iPhone 6s for three days now, and I’ve still not found the feature or cumulative performance improvement it would take to get me to upgrade from my iPhone 6.

I’ve heard Apple (and many other reviewers) gush about things like speed and camera improvement, and I don’t doubt that many things are better in the new phones, but I do question how meaningful the improvements are in everyday use.

As a continuation of our Friday review of 3D Touch and the cameras, let’s look at four more important features of the iPhone 6s.

Processor speed

Yes, the iPhone 6s is the fastest iPhone ever. Well, it’d better be: I don’t imagine Apple will ever release a flagship phone that’s slower than the last generation.

By some measurements, the iPhone 6s’s A9X chip puts Apple well ahead of the competition in the mobile processor race. This is important because it will future-proof the phone for future resource-hungry apps and services.

An Apple rep told me that the new iPhone uses the same SSD (solid state drive) controller (which controls when and where the phone stores data) as the one used in the MacBook. That alone makes a big difference.

The people over at AnandTech released a battery of benchmarking tests that confirm the iPhone 6s’s speed relative to the iPhone 6 and to other phones on the market. The iPhone 6s doesn’t win every benchmark; it’s well down the ranking in tests of the speed of random input/output. But Apple’s A9 chip has clearly been souped up and optimized to make the Safari browser sing.

And the interplay between the CPU and GPU in the iPhone 6s creates some incredible graphics performance. “The A9’s PowerVR GPU is actually beating the iPad Air’s GXA6850 GPU by a significant margin,” AnandTech’s Joshua Ho pointed out.

But on many of the benchmark tests, the good old iPhone 6 isn’t far down the list from the new 6s. I’ve been doing some side-by-side testing to look for speed differences. Some have talked about how lightening-fast the 6s’s fingerprint reader responds to touch. It is fast, but it’s not instantaneous. There’s still a beat between the finger touch and the log in. You’ll find the same little pause on the iPhone 6, and that pause isn’t very much longer than on the 6s.

App launching is the other oft-used measurement of the speed of a phone. It was easier to see a difference in the time between icon touch and app launch — the iPhone 6s is faster, but by milliseconds.

Some have said the OS on the new phone “feels lighter” because the A9 chip is running it faster and more efficiently. That too, is noticeable, but not by much, and I never noticed my iPhone 6 running the OS in a sluggish way.

I also tested the Safari browser running on the iPhone 6 and iPhone 6s side by side. When I clicked on a link to an HD promo on YouTube, I could see right away that the 6s’s browser launched the video faster. When I paused the video at the exact same time, the video on the 6s was at the 26-second mark, while the one on the iPhone 6 had reached the 25-second mark. In a second test, however, the videos ran so closely together that the characters in the scene spoke in perfect unison.

The Display

The display on the iPhone 6s might be the best I’ve ever seen in a phone. I’ve been very impressed this year with the displays on new Samsung phones, like the 577-pixel-per-inch HD super-AMOLED display on the Galaxy S6. Samsung is very good at making displays, as it demonstrates in its HD TVs. I noticed a trend, however, in this year’s displays where the image is simply brighter. This effect alone can give the appearance of a better overall image on the small screen of a mobile device.

I believe Apple went a different direction. When you watch the same video on the iPhone 6s and the Samsung Galaxy S6 Edge, the picture will look more luminous, and maybe a little bit sharper, on the Samsung screen, but not necessarily better. The picture on the Apple screen has a mellow, refined look, a more lifelike white/dark balance, and the transitions between light and shadow seem true-to-life. The colors are more rich than vivid. Overall, the iPhone 6s screen is more pleasant to watch.

Is it a better experience than that of the iPhone 6? Yes, noticeably. But when I go back and watch video on my iPhone 6 after spending some time with the 6s, I don’t feel deprived of anything. The video quality is still very good on the iPhone 6.

4K Video

The 12-megapixel rear-camera sensor on the iPhone 6s can shoot video at full 4K high-definition resolution, although it’s a good idea to keep close tabs on your storage space if you shoot a lot of it. One minute of 4K video will cost you 375MB of space. The existing iPhone 6’s 8-megapixel camera shoots 1080p video.

While 4K does offer a better, sharper look, for many consumers the new feature won’t make an immediate difference, as relatively few have purchased the new 4K TVs or monitors needed to appreciate the higher-quality video.

While the iPhone 6s has a great display, I was still hard-pressed to tell the difference between a video of my cat I shot in 4K verses a very similar one shot in 1080p.

Live Photo

With Live Photo, Apple attempts to put a little visual context around your photos. To do this, the camera extends the capture moment to 1.5 seconds before and after you hit the button. So, the total shot is one frame plus several “contextual” frames on either side of it. When played in sequence it looks something like a short movie, although Apple says it isn’t actually video.

While the feature has received a lot of attention, I doubt it will seem like a big deal a couple of months from now. It’s just an interesting little add-on, sort of like screen animations in the OS.

Fortunately the feature doesn’t seem to chew up a lot of memory. A photo I shot using Live Photo was 1.9MB, while the very same photo shot with Live Photo turned off took up 1.7MB of space.

I’ll have more commentary on Apple’s new device in the coming days. I’m $815 lighter now that I’ve bought my new iPhone 6s. And while I’m enjoying using the phone, I’m not so impressed that I’m going to throw away the receipt.