I have the 32 GB. It's great. I've had iPhones since the 3G (which is the 2nd-generation iPhone two years ago), and this one is by far the best. The screen alone makes it a worthwhile purchase because it is leaps and bounds better than previous iPhones' screens (640x960 pixels compared to 320x480). The only drawback is the "antenna issue" which is only a problem when you are in a low signal area. You can request a free case from Apple if it bothers you.
Overall, it's the best iPhone yet.