Make sure you get into an Apple store to see the device in person. Between the display and the fit and finish it will probably blow you away.
Remember this on the signal issue:
1) "Death grip" results in about 20dB signal loss. This is comparable to (but yes, a bit more than) what happens on other phones.
2) The "bars" display is currently miscalibrated: you can have 5 bars and actually have a rather poor signal, in which case the 20dB attenuation kills you. Or you can have a strong signal showing 5 bars and that 20dB has no effect.
3) The iPhone can eke out a strong connection at weaker signal strengths than other phones due to improvements in overall RF design.
4) It's still probably best to try to remember to keep your fingers away from the seam on the lower left if you're not in a skin or a case.
Source:
http://www.anandtech.com/show/3794/the-iphone-4-review/2
So don't sweat the reception issue. Now it's down to hardware design (and the unbelievable display), your philosophy about Apple's curated app store, your OS preference. IMHO Apple wins on those issues.