I never really got into DS9 when it first aired, so I've decided to watch it. Currently on season 3, and so far my feelings are mixed. The storyline is interesting and the characters are ok (admittedly, I'm having a harder time connecting with them than I did with the TOS and TNG crews), but it's nowhere nearly as gripping and interesting as, say, Babylon 5.
I've heard that the last four seasons are quite a bit better than the first three, so hopefully that's accurate. I wouldn't say it's been bad so far by any means...just not exactly captivating.