ArsTechnica,‘s comprehensive, multipage (with loads of photos) iPhone 4 review. Downsides:
The glass on the front or back may break if you drop it, though that’s not a particularly new development in iPhone land. FaceTime chats only work with other iPhone 4 users for now, and may not work well if you try it at work. The HD video is generally not as good as what you can get from an HD Flip camera. The OS and native app situation is still quite locked-down under Apple’s sometimes-questionable policies. Finally, if you hold the phone funny, you may degrade your own call signal.
Upsides:
The 326ppi display is one of those things that turns you into a dirty Apple lover and makes your friends begin to plot your death. The camera is top-notch. Battery life is improved over the most recent iPhone models. Even the data speeds are faster than previous iPhones with 3G thanks to the addition of HSUPA. The ability to take HD video at all is a nice benefit, and FaceTime calls are at least fun (if an old concept and possibly useless). The hardware is fast—even when compared to the already-speedy iPhone 3GS.
To hold it is to want it. To use it is to love it.