It's sad to say but some angie's list members have been using the rating system to vent their fustrations, and misfortune with past contractors.
So i would say believe half the bad reports out there. Especially do to the fact competitors, could have friends/family leave false reports. Make your own mind up, call the company that you originaly wanted to use, and ask them about that review.
I can bet that half the stories out there about bad contractors, are begun by customers who don't want to pay their bills, don't pay their bills, or feel as they are so special they should not be charged, and want everything done for free.