mtbr.com has a review section as well as this forum. This is a good way to do a little research on bikes that you are interested in.
Research is a VERY good thing, but nothing beats riding and talking to as many friends and LBS as possible. Be weary of on line review…Pay attention to the person who did the review, how long they "rode the bike" and if they have owned other bikes.
I get a kick out of people who go to a LBS ride a FS bike around the parking lot and give it a bad review saying it does not climb or handle well. How would they know? Or people who have never ridden a Mountain bike on a trail giving reviews is like asking a 12 year old for a review on how a BMW drives???