Complicated is good.
Complicated is good, but too complicated is bad. It's a fine line to walk. And I guess if Moffat crosses over into "too complicated", well, that just increases the DVD sales. Win-win for him.
As for the episode itself: I loved it. Probably my favorite episode so far this half-season.
EDIT: I do wish that whoever tracked the music did a better job, though. They didn't seem to understand that they were using the Doctor's theme, not just generic action music...