Bigger isn't always better. But in Legend of Grimrock 2, it's better most of the time.
They've kept what made Legend of Grimrock great, rectified some of its failings and generally expanded much on variety and content. The latter brings a failing new to Grimrock. Some of the puzzles and their clues span the game world and can require quite a bit of backtracking if you missed some clue along the way, or didn't bother writing it down.
But these incidents are few and far between compared to all the goodness this game has to offer. New dangerous-looking enemies make it harder to dance around the less-than-up-to-it AI of the first game. I won't spoil it for you, but some enemies were just genious. The new environments, including outdoor ones, are varied and beautiful. New puzzle elements bring spice to the old formula, allowing you to feel different kinds of clever upon solving them. (Or different kinds of stupid!)
Class and skill systems have been revised, with additional classes and a new race - the ratlings.
In short, if you liked the first one, you're gonna love this one.
9/10