Because nothing could be worse than the third one.

Andrew Garfield is pretty good, and pulls off a dorky Peter Parker better than Maguire did. Gwen Stacey is cool (and very pretty). Some of the scenes were kind of awesome, and some of the action was really good. They did pretty great web-slinging, it seemed more realistic and physics-based than other on-screen versions I've seen.

And then other parts were just ... goofy, or cliche, or weird, or hand-wavey plot-holish. I won't give specific examples here, for that way lies spoilers. But there was really too much dumb stuff for me to call this, on the whole, a great superhero movie. It's a mediocre superhero movie that has its moments, and it's a pretty sweet take on Peter Parker. Not worth full price if you can see it at a discount.

I'd give it a 6.5.