There is definitely a need for a website like this. Right now the way strains are rated is terrible and tells you nothing about what the effects are actually like. Usually the descriptions just say something like, "uplifting and energetic" or whatever. Meh. My criticisms would be:
1) Explain how the rating system works. It's not obvious just by looking at it that you only get five point to allocate within each category.
2) Consider bringing the rating system more in line with the academic research, specifically with the book On Being Stoned.
http://www.druglibrary.org/special/tart/tart8.htm
http://www.druglibrary.org/special/tart/tart11.htm
There are several chapters worth of different effects, and since each strain is fairly consistent in its effects I think it makes sense to at least give users the chance to fill out a lengthier survey.
3) Bad design. Good design is supposed to remind you of something. This doesn't remind me of anything. Except maybe a generic web 2.0 looking site like OMGPOP. I'm not sure what the right look and feel is for a cannabis ratings guide, but I'm pretty sure this isn't yet. Maybe something that borrows inspiration from Zagats and Google Maps? You need a design that signals to a first time visitor that this is the authoritative site for this information, and this design doesn't send that signal at all.
4) If you want to start a marijuana-based web startup then you should make software for the dispensaries. This is enormous demand for this and it's completely unfilled. As a website I like leaf.ly conceptually, but as a startup I think it's most likely a really crappy idea.