The controls feel slightly sluggish, but it's fun, particularly the ending, where Zak flings himself headlong at an alien god armed with nothing but a steel pipe and brass balls. 100% completion is a rewarding challenge. The resurrection sound effect is giving me pazaak flashbacks, though.
Great fun despite a couple of annoying things: the "End Now" button often giving the wrong results and your player taking a shot when you try to unpause the game.