I'd like to check your logic here a bit. I can't put this together. Can you explain why you want reviewers to create an account? I know that it's not required. I'm just wondering why it is something you're interested in. Just think of that question and put yourself in their shoes. What do they get if they sign up? Another important question is, what profit do you stand to gain from this side of your user base?
I feel like the majority of your traffic (and thus the most likely source of revenue) is going to come from people reading reviews because they will want to browse several colleges to read what alumni think of them. I suspect that most reviewers will only ever make 1 review and therefore give you roughly 2-3 page views ever. But that one review may get read thousands of times in the future by unique visitors. You simply can't afford to scare away a single review. It needs to be really simple.
Basically I'm saying that you need reviewers to create content before you can even begin to attract the traffic which could possibly provide some revenue for you later on. So make it dead simple for them to do that. Don't have them make an account cause they'll never come back. Why would they? They've already been to college and they already reviewed their school. Just give them a search field to find their school and set them on their way to voting/reviewing/doing what ever you need them to do to make this site work.
- enter your name and your review for the school, period.
Thank you for your valuable input, I did the mistake I was trying to avoid in the first place : put the code before the user.