I've never been quite as big a fan of Forbidden Planet as some (except for Anne Francis's legs, which would make any movie worth watching). I actually like all the pop-Freudian stuff that some critics complain about; pop Freudianism is so much a part of '50s culture that it would almost be wrong for the movie not to do that kind of thing, and the psychoanalytic approach to sci-fi is a nice change of pace from the usual '50s sci-fi movie, which usually dealt exclusively with the question of whether or not we could trust alien invaders; Planet is about whether or not we can trust ourselves, and that's actually more interesting.
My problems with Forbidden Planet are more technical and structural. Structurally, not a lot seems to happen before we get to the pop-Freud stuff; it really needed some cutting down, because there's so little action and so much talk. And on a technical level, the movie could have used more pizazz in the design concepts -- except for the design of Robby the Robot, nothing in the production design sticks in my head as really memorable. And the direction, like a lot of early-Cinemascope movies, is a little slow and stodgy. Throw in the silly electronic beep-boop score (electronic music is fine, but this isn't good electronic music; a good orchestral score would have worked much better and given more propulsion to some of the slower sequences), and you've got a movie that is sometimes more fun to summarize than to watch -- particularly when Anne Francis isn't around.
But, that said, I'm still probably going to get the special edition DVD set this November.