Compare him to Pudge if you want, but both those catchers are overall 'flash', IMHO. Pudge's interview in SI a couple of years back where he admitted he never called his own games took a bit of shine off the old bronze statue for me.
I've heard Piazza-as-catcher defenders before maintaining that pitchers have never complained about his work behind the plate, and may have even complimented it. With respect, how many MLB pitchers have you heard complain about their catchers? (Heck, I didn't even hear a word about AJP from Giants pitchers last season, and I was appalled by some of his antics.) And didn't the second reel of Bull Durham teach you about baseball cliches and what to say in an interview regarding your teammates?
Piazza provides serious O, and I'm sure his pitchers appreciate that. That makes him a star hitter, but it doesn't make him a star catcher. If he's behind the plate, or on any old tapes of him, check out the footwork. Check out his balance on plays at the plate. Do you know that the pitchers are comfortable throwing all their pitches in any situation with him back there?
If you want to talk about MLB catchers that young players should emulate and listen to for defensive and pitcher-handling purposes, Piazza would never make my list. I would refer them, again, to Matheny and Ausmus.
And I would suggest that those who hold up Piazza as a defensive catcher haven't been paying attention during the games.