The effect of having a thumbs up or down feature as it is now seems to be nothing more than an exercise in expression, with some small feedback and monitoring value. That is, the poster can see how others are reacting and others are able to see what the thumb voters chose to express. In all, there's nothing wrong with that, but I think the feature could be more valuable.
Recommendation: The overall weighting of Thumbs up and Thumbs down are indicated on the home link page. So, when you see the thread listings, you can also see if there's a Positive 16 thumbs up for the thread or maybe a negative 12 thumbs down for the thread. That might be a little complicated to do, but it would really help to inform a member whether or not they might like to visit the thread.
Just s thought.