Yeah, the acting is pretty stiff in the first season and bad at times but once you get into the middle of the series I think you'll be impressed. I have a feeling deep down inside every hardcore TNG'er is a secret Niner inside. DS9 is a wild ride. Bonus if you are already a fan of Worf.
Keep your eyes on Odo. He's an excellent character and unlike the others, I think Odo was playing quite well from day 1 by Rene. He did a terrific job of shapeshifting Odo into a classic Trek icon.
Once really nice thing about DS9 in particular is that the strength lies in the ensemble cast. And the stories vary considerably: serious Bajoran religious stories, exciting Starfleet-driven battles and silly Ferengi outings. The feel of the show could be radically different from week to week... I always found that refreshing.