Controls are intuitive and responsive, and the level design is challenging while still being fair. Closest thing to a problem is how the block enemies can move on their own, but you can't move as them when you possess one, so that takes a bit of getting-used-to.
Wow! Just wow! I enjoyed the experience. It's a shame you can't run, but I understand the gamedesign idea behind this. A cool little game, strongly recommended for SCP lovers.