First things first, I didn't see it in 3D as there were issues with the screen. However, not being an enormous fan of 3D, I can't see that the movie lost anything by being in 2D.
There is a rule in storytelling that states you should always "show, not tell". It basically means that you shouldn't leave it up to dialogue between characters to explain what it is happening. The first half of Man of Steel is made up almost exclusively of scenes showing two people stood face to face, having serious discussions. With little flow between scenes, these felt stunted and somewhat dull. It was also true that you often wondered how the characters had ended up where they were as scenes were cut together in such a way that showed little progression between them.
When the action finally kicked in, I admit that the effects were sensational. I'm not a fan of CGI, yet it was done beautifully in Man of Steel. However, the fight scenes largely seemed to consist of Superman flying through a series of walls, clinging onto his opponent. This was fine, but after half an hour it became a little predictable and you had to wonder about such wanton destruction by our hero.
Superman is a difficult character to make interesting. Thanks to his moral integrity and farm boy upbringing, he has always been written as the perfect American hero. The writers of Man of Steel have tried to combat this by including a complex relationship with his Earth father. Unfortunately, this is handled clumsily and, rather than add depth, it makes you want to give Clarke a clip round the ear on occasions. Then, towards the end, Superman faces the ultimate moral dilemma, which felt a bit shoe horned in. Also, his actions are necessary, and so you lose the element of "ooh, did he do the right thing?".
All in all, Man of Steel takes itself very seriously. And that's ok, but it would appear that someone read through the script and decided that there should be a few funny moments. As such, there are three or four attempts at dead pan one liners that don't happen regularly enough to sit anything but awkwardly with the tone of the film. This isn't helped by the repetitive and heavy score, which serves to remind us that, for 143 minutes, there is nothing to laugh about here. Superman should leave the one liners to Tony Stark.
Also, Russell Crowe is in it. Enough said.
There are, of course, good points. As mentioned, the effects are stunning and there is a bearded Henry Cavill without his shirt on. Sadly, although the plot had the potential to be simple to follow yet engaging, my concentration waned after the first 60 minutes of watching people stood around having a chat.