Upgraded from an iPhone 3G (OS 3.0) a few days ago, which I’d been very pleased with for the whole year I had it. Paid for the 3G S in full, as I wasn’t due an upgrade from O2.

Like many other reviewers, I’m simultaneously impressed and underwhelmed. In the end it looks and feels like an iPhone 3G, but it also comes with some very useful improvements.

The video and camera auto focus are very nice additions. The video is roughly the same quality as a Flip Ultra, although I don’t think the microphone has quite the same range as a Flip (haven’t done a side by side test though). It’s going to do a good job of capturing social or family events, where a proper camcorder would be overkill.

The photos are a big improvement over the 3G (I did a side by side test for comparison purposes); much sharper, and the touch controls for focus/exposure are brilliant.

The speed isn’t a big deal on simple apps, but it’s night and day on 3D or data heavy apps apps. Google Earth, Evernote, and Spotlight are completely transformed. Safari is noticeably faster too.

Often with the 3G, the phone would stutter occasionally as it was presumably running some background task while dealing with your input, and that’s much less frequent on the 3G S.

App load times are much better too – 1/2 to 1/3 of the old time. Obviously you notice this more on the bigger apps. 3D games also run significantly better.

The compass is nice, but so far it’s just a novelty. Hopefully some 3rd party apps will start to make good use of it soon.

Basically, it’s an upgrade for power users, but probably a waste of time for most 3G users (at least at £200-300 for the upgrade). The harder you push the phone, the bigger the difference in performance. Hopefully this will bode well for future apps.

For new contracts, the choice is easy; the 3GS (16Gb or 32Gb) is a much better deal than the 8Gb 3G, despite the 3G’s lower price.