Sorry, but the Id Monster: No. Just No.
I can understand the producers wanting to break new ground and get away from puppet creatures and stop-motion, but that Disney-derived cartoon monster just doesn't have any gravitas. I saw it in a theater in a limited run/re-release (along with The Time Machine) in maybe 1975. The creature didn't convince even on the big screen - nor does it work in the HD version. A cartoon is a cartoon, and after the massive creepy build-up to the great revelation, we get a sort of cross between Warner Studio's Tasmanian Devil and the Bald Mountain monster in Fantasia. It was a big disappointment in an otherwise very fine film. Botching the central villainous character/central special effect really brings this film way, way down.
Related issue: the Id Monster seems to be huge when we see it illuminated by the perimter beams. Yet before this scene, it is able, invisibly, to get aboard the ship and murder the chief technician. And when it first visits the ship, the camera runs up the stairs to indicate its stealthy entrance. But in its major, lethal, visit, the camera shows the steps bending under its weight.
So are we to gather that at first the monster was smaller and lighter and only gained hugeness as Morbius' unconscious jealousy over his daughter's attraction to Nielsen... or what?