It finishes it off for the most part, but the door is left open for some more books in the same world. The main story arc is all done though.
I'd read the follow-ups, only because I think Ryan can still write his ass off, he just really needed an editor to help him out on this one in terms of the storyline. Someone should have stepped in and told him that his outline was lousy, and that you don't introduce like two dozen new generic-fantasy-named characters in the third book of a trilogy. Crappy plot aside, I spent a good deal of time thinking "Who the fuck is this person again?"
And shit, I read Malazan twice. I like to think that I can keep up with a big cast.