Upon a search of Google, there are a number of reviews sites such as this. Most of them only review older guns (they are semi-outdated sites), but you can usually get a range of different opinions just by reading threads in these forums. I think just reading the forums is a better idea because you'll get a more extensive feel for how the gun operates and what playing styles would go well with certain guns. Search for a gun and take a look. If you're still adamant on a review site have a look at this
http://nerfcenter.com/reviews.htm; from what I've seen they have the most guns reviewed out of any review site, lacking only some of the newer guns and non-Nerf guns.
Edit: You'll find that a lot of guns have a fan-base even if they are considered by most to be "crap". You'll also find a lot of horrible stock guns that can be beastly once modified. I guess it's all subjective
Edited by Militant Panda, 03 November 2007 - 01:18 AM.