Been using my iPhone 4 since early Thursday morning and I've noticed a few things that have pleasantly surprised me. Battery Life / Bluetooth. Yes, I knew the battery life was supposedly improved, but I had my doubts that it would be noticeably better. I'm happy to report that there is a BIG difference, especially with certain functions. For example, I've noticed that using my Bluetooth A2DP headset uses MUCH less battery on the iPhone 4 than it did on my 3GS. I listen to music and podcasts for hours every night at work, and with my 3GS, I would normally be down to minimal battery life by the end of my 8 hour shift. I usually turned 3G off when I first started work since it saved battery life. However, the last couple of nights with the iPhone 4 - with the exact same usage - I still have over 60% battery life left and I haven't even turned off 3G! Tonight, I started at 100% like usual and I even listened to streaming music for a couple of hours using Slacker and I was still at 60% when I got home. I have also noticed that the phone takes less time to connect to my headphones as well. GPS. I've noticed that the iPhone 4 has noticeably better GPS than my 3GS. Specifically, it seems to be more accurate and does not wander much at all, whereas my 3GS would often be off a bit as well as wander or lag sometimes. The iPhone 4 is probably using the same GPS chip that the iPad uses since we noticed an improvement on the iPad as well. Furthermore, it's nice being able to use another application while GPS is still functioning. On the way home from work tonight, I had MotionX GPS Drive running while simultaneously streaming music from Slacker and they both worked flawlessly. The music would still duck while the GPS' voice was heard, and I could switch to other apps while they both were running. Nice! 3G Upload Speeds. I have noticed MUCH faster upload speeds on the iPhone 4. I don't have my 3GS activated anymore to do a side by side comparison but I'm often getting close to 4500 kbps down and 1600 kbps up, whereas the 3GS would be lucky to get a few hundred kpbs up. Admittedly, I'm in a good 3G area (Quad Cities, IL/IA) but these are some good speeds for 3G! Here's a link to a video showing the speed tests: http://www.youtube.com/watch?v=hCCbFXLaNIQ Overall, I'm very impressed with the phone and it's nice to find some surprises that weren't as obvious as things like the retina display and unique form factor.