I felt that Grimrock 1 was more coherent, than Grimrock 2, in the way it was constructed, though I suppose that's down to the fact that the former had but a single dungeon.
Some of the flow must be sacrifice to get a decent, thouroughly enjoyable, outdoors experience I guess.
All in all, an amazingly enjoyable game through and through, though I still like Grimrock 1 better (gotta replay that someday soon).