Maelstrom contained about a dozen of what i'd consider "true" animatronics. Special mention to the three headed troll however since it has a lot more motion than others. There's a lot of other figures with a bit of motion, but it's pretty much just one axis of motion (like the puffin heads turning or troll heads rising up out of the water).
Frozen actually slightly upped the amount. I counted 15. Though unfortunately, they're all the crappy face-projected variety, and Frozen isn't one of the few rides they look decent in (Tokyo's is getting physical faces thankfully, and i'm guessing probably a far better ride in general).
The scenery in particular suffered tremendously in the conversion. Maelstrom had a few areas that had lapses in scenery and were too empty or exposed the backstage areas (like the hallway and door transitioning into the three headed troll scene, which Frozen itself didn't fix either). But it was still a LOT better than Frozen's scenery. There were some exceptionally beautiful and detailed backgrounds in several of the scenes. The viking village and beach especially, and the area with the three headed troll. The track switch scene right before the final drop was also extremely lovely in comparison to Frozen's plain snow.