I went to prom. However, I was in a very small school, with about 50 students in a year, so even though we didn't all get along, it was a small, tightly knit community. Also, he didn't have any other forms of formal dances (like homecoming), so it was a pretty big deal. All in all, it wasn't the torture I thought it'd be (I wasn't exactly the popular, social type). I actually had fun, got to wear a pretty dress and get my hair done (which is fun, once in a while, I guess). Didn't go to the after prom, didn't get wasted, though.
In conclusion: go if you want to go, don't go if you don't want to go. Prom has no reason to be a rigid rite of passage everyone says it is.