Uh... actually I'm gonna have to agree with Calendar Man. As big a Spidey fan as I am, I have to admit the first film was a mess. Due largely to a hand-me-down script that suffered too many re-writes, unperfected and unnecessary special effects in many places, and general laziness and poor attention to detail. I remember being so hyped for that film, and was totally embarassed when I sat through it with my friends and family. I own the film, but I don't watch it. I can't watch it. It makes me cringe.
Spider-Man 2, on the other hand, was great. There were a few things I would have done differently, but overall it corrected almost every problem the first film had. It's a movie I actually really like to watch. Leaps and bounds past Spider-Man 1.
How Spider-Man 3 will turn out is anyone's guess. They're going with a very different type of villain this time (supernatural rather than realistic/human), and that could completely change the tone. Maybe it won't. Who knows. But as far as the quality of the filmmaking, I'm sure it will be on par with, if not above, SM2.