I feel that a 3-star rating for "X" says a lot, actually. Of all the titles on MGM's Midnite Movies roster, it certainly has the most entertaining and though-provoking story. Surely every person at one point has fantasized about being able to fly, being invisible, having x-ray vision, etc., but what would really happen if you were granted one of these powers? And are you certain you could control it? Here's your answer. Corman's direction is not too shabby - although some of the dialogue is extremely stilted, the cast gets through it with barely a scratch. I've seen Ray Milland in some real stinkers, but his acting skills have never been in question. While he plays a stuffy doctor very well, this film has some humorous moments where his expression or tone of voice speaks volumes... cocktail parties never looked so fun.
The special effects, for the year and the limited budget, are not that bad. They did an acceptable job of conveying what Dr. Xavier was seeing, and the physical transformation of his eyes in the last half of the film is well-done. It's a shame that the movie didn't go into more detail on the "object" (no spoilers here!) that he sees at the limits of his vision. That was a very interesting plot point and could have provided even more weirdness.
As a long-time fan of The Twilight Zone and The Outer Limits, I certainly recommend this film. The only problem I have with it is the ending. I truly want to believe that the rumor regarding the deleted final line of dialogue is true. Even if it's not, I think Corman and MGM should have played along and tacked on a dub during the fade-out, especially for this DVD edition. The ending, as it is, is chilling but lacking, and it's too abrupt. Adding the infamous deleted line would add an entirely different scope to this film.