As far as what Phoenix has to offer, this is definitely the best comic book store to go to. This location in particular is the best one in the valley.
I've been frequenting here since I was in the fifth grade and I've yet to be disappointed. What's great about this place is that they have all the current issues available as well as a strong collection of back issues. They're also pretty good about maintaining a solid manga section as well. Another reason worth stopping by is their "indie" selection ala Jhonen Vasquez, Charles Burns, Clowes, etc..
If you can't find it here, they'll order it for you so you won't lose any more sleep about what Superman said to Wonder Woman in that one issue of Red Son or whether you can find that favorite issue of Toyfare that you lost in junior high.
If you're looking for a crash course in geekdom, you'll find everything and more here. The staff is pretty knowledgeable and friendly if you're looking for something in particular or even if you're just wondering what's good to read. This place is definitely a staple of Phoenix and isn't leaving anytime soon.