I love the quest line, the mystery, the conspiracy, and even having a jail break reminiscent of Call of Duty: Black Ops. It's a great story line but the city itself...I don't know. I guess I stick around Markarth only because of Muiri. The City is a pain to navigate, at least for me.
I don't like navigating the city either, so I don't really go there that often. But that kind of makes sense with the quest (if you sided with the Forsworn) because you really wouldn't want to go back to Markarth for a while after breaking out of prison and killing all those guards. It is a cool looking city though, and I like its nickname,
the city of stone. It reminds me of Gondor actually, and so does Whiterun.