Some people do think DS9 is a "betrayal" of Roddenberry's vision of Star Trek and don't give it the time of day. That's their opinion.
I personally think it's the best of all the Trek series. There's drama, conflict and the human condition is really explored in a way that none of the other series do. To say nothing of excellent story arcs and character devolopment. Just watch Emissary and What you Leave Behind back to back for a reminder of how everyone really changed and grew over those seven years.