Very enjoyable, on the whole very good - some elements of the direction were impressive - but not quite the whole banana. Could just be that I don't rate Superman that highly as a superhero - too much of the boy scout compared to Batman - but after an excellent first half I found the second half underwhelming.
However, some cracking moments contained within, my favourite being right at the beginning, with the destruction of the train set (pic above). That was truly sinister, a wonderful piece of cinema - not surprising that the rest seemed less exciting after that. (It would have perfectly set up some real city destruction as the film's concluding drama - as it was, the creation of a new island was rather bathetic.)
Worth watching though. Spacey is excellent.