I don't really think Verizon's ads are "misleading". They state CLEARLY that it is a comparison of 3G coverage areas. I would argue that one of the greatest parts about the iPhone is its web-browsing simplicity, and 3G, while not necessary, is a huge part of the customer experience on the iPhone.
In addition, I think it's nice to actually see some head-to-head advertising; I hate the "blah blah blah XXX is 25% better than the national leading brand". I want you to tell me how your product is better than the others, and doing so often necessitates a direct comparison to a specific product or brand. I see nothing wrong with the Verizon ads.
FWIW, I have been on AT&T service for ~5 years now (in Oklahoma), and I don't have any complains from this part of the country. Verizon does not provide new accounts in this area, though I'd have no reason to switch anyway. Much like real estate, whether one wireless provider's coverage is better or worse than another depends primarily on your specific location and where you travel. For me, AT&T has very good coverage around here (and in the areas to which I travel), while Verizon is shoddy. You can discuss the pros/cons of the technology each uses, but unequivocally saying that VZ is absolutely better than AT&T isn't justified, IMO. It may be better for you where you are located, but it certainly isn't for me and in my area.