Worth getting if I own GTA IV?

I agree I would not say that one would necessarily cancel the other out and they are different enough. Many people do not really care much for Chinatown though and I tend to fall into that category myself so just try it out.

 

I believe this is the worst reviewed GTA game. You're not missing much if you don't get it.
And I don't see the connection between this and GTA 4.