Reviews plugin

Hi Guys .

I just installed a magazine type theme and am writing product reviews - I would like to allow people to register at my site through facebook or setting up email / password and then have the ability to add their own ratings of the products and add their own reviews and comments as well.

I was investigating Buddypress but it seems that it might do more than I actually need and my theme would need some customizing.

Can you make some suggestions on the best way to achieve my goals - If you want and example to look at http://www.rottentomatoes.com is a similar idea.

Your help would be greatly appreciated !
Many thanks

Kevin