I really liked it, and I went in with rather low expectations. I'm one who really liked the the first trilogy with 3 being by far the weakest, and I think this first one is much better than the other first one. It felt more serious yet it stayed comical just enough. It makes the first one seem downright goofy. Comparing the second movies in each franchise will be the real key, as I think SM2 is definitely the best of the original.
I actually feel bad for it a bit since its timing of release. It's sandwiched between 2 of the biggest, most anticipated superhero movies ever so I'm not surprised it's been somewhat overlooked.