Have you made a decision yet? Please forgive me adding my two pence worth.
I bought a San Fran. to replace another 3G phone that broke within a few weeks of purchase and so far have been very impressed. As
finaly noted the unlock code is free and very easy to use, taking about 30 seconds to fully unlock the phone. Out of the box the OS is skinned with a hideous smokey orange and grey colour scheme but an application is pre-installed which allow you to switch this over to the default Android skin and more stylish alternatives are available in the Android Market. The screen is clear when compared to similar phones such as the HTC Wildfire and video playback looks great. Call clarity is reasonable for the 3 network in my area.
There has been some occasional juddering when switching between different home screens and the touchscreen sometimes needs more pressure than might be expected befor finger contact is registered. The camera is nothing to write home about, the phone can sometimes struggle to get a 3G signal in areas where my old 3G phone had no problems and music playback using 3 (aka "Cubed") can be a bit clicky at times.
The phone ships with Android 2.1 but,
as noted, beta version 2.2 ROMs are available in the wild. As with all beta programs (and especially unofficial ones) some problems have been reported by those brave enough to test them so it may be worth waiting until more stable versions emerge.
Overall this is a great little phone for the price and you certiainly get more than you pay for.