That was pretty much my initial reaction too. I don't like not knowing who the characters are. Yeah I thought the movie was cool the first time around, but once I understood what the fuck was going on it was that much better.
See, in the series they only touched on the topic of Reavers. It wasn't the main story or anything like that.
Taking just that story from the movie though, yeah there are better "OMG WE CREATED A MONSTER" ones out there.