As another data point, my Droid GPS is more accurate and stronger than my brother's iPhone seems to be (non-scientific comparison while geocaching).

However, the Droid has a well-known problem where the GPS won't lock or will give bad data. For instance, I was on a freeway in south Texas a few days ago and it said I was in Colorado moving at 370 mph. Was wacked out for half a day, even with several cold reboots (battery removed). Then, all of the sudden, it started working again. I found many descriptions of similar behavior online. Verizon and Google are both pointing fingers.