I never watched DS9 when it was on TV since the first two seasons didn't interest me that much. Boy, did I miss the boat! DS9 is really cool. I purchased the entire show on DVD and love it! To be sure, there are good episodes and bad ones, but I really enjoyed it. It really gets interesting after the third season and it is much better to watch without all of those anoying commercials.
I have to admit that they best Star Trek battle scenes are in DS9. If you like action, DS9 has it in droves.