I watched the TV series before seeing the movie, and the movie would be difficult to follow and understand the interworkings of the background of the characters. The movie was definately designed, in my opinion, to be for the fans of the series who had seen the character introductions, understood who this crazy girl was, and why she and her brother were on the run, etc...
I think that the upcoming Stargate movies will be similar. They are designed for Stargate SG1 fans, and not for someone just coming in on the end of the series, but that is a different topic.
I actually liked the mix of wild west and future sci-fi. It was a fresh and innovative approach to what amounts to a lot of boring "same ol', same ol'" TV...
