I'm fine with likes and dislikes, as long as they're not anonymous.
I've been a avid member of the Arcade-projects forum since it's start, and we've had a like/dislike system there for a while now. It works really well. There is practically no drama on that site, people treat each other with respect, and there aren't any members that use their life situations and opinions over others in a malicious, condescending way.
Likes and dislikes are listed on the posts that receive them, and it's easy to see if someone is repeatably throwing a dislike onto someone just to troll them.
As long as the member's names are listed for likes/dislikes, it shouldn't get out of control.