I've been meaning to see these movies for a while, so when the chance came up to buy all of them, I had to go for it. I have already seen Superman 1 and 2 and they are both great. This review would have been 5 stars if it wasn't for Superman 3 and 4.
I personally felt that Superman 3 was the weakest of the series, with Superman 4 not far behind. The first main problem the Superman 3 is that Lex Luthor is not in it, he brought a bit of comedy to the films with him proclaiming that 'he is the greatest criminal mind of our time' and so on, but without him in it, the movie seemed a bit bland.
Another thing about Superman 3 is that we get to see his dark side, which sounds good on paper, but it isn't pulled off very well and the fight between bad Superman and Clarke Kent is laughable (for the wrong reason) and drags on too long.
Superman 4 sort of made up for the shocker that was Superman 3, but not by a lot. The best bit is that Lex Luthor is in it, so that relates it more to the first two films, but thanks to a sub-par supervillain in the form of Nuclear-Man. But Superman 4 also gets bonus points because it sends a message out about nuclear weapons, and I found that it worked quite well because it was woven into the story and not thrown together as an afterthought.
Overall, this boxset gets 4 stars. The first two films are excellent, Superman 3 was a huge dissapointment, and Superman 4 was also a dissapointment, but it was at least better than Superman 3.