I'm going to get blasted for this I know it, but:
I really did not think this movie was that bad. In fact, I would easily rate it as the second best Superman film under Superman the Movie.
The plot, while not exactly an action packed story, was sufficient, and I understand how Singer wasn't going for the same action level as we were used to. He wanted to show just as much of Clark dealing with coming back to Earth and dealing with the changes around him as he wanted to show Superman saving the day.
After watching the film for the second time, I really began to get used to Routh as Superman, and I admire his dedication to the role, especially stepping into such big shoes after Christopher Reeve.
Kevin Spacey was perfect as Lex, I can see no problems or complaints whatsoever.
Lois could have been a little stronger but overall she fit really well with the general tone from the original films.
Overall, yes there were some moments where you were expecting a little more, but I generally enjoyed the film and believe it to be an excellent piece.
Now notice, my attitude has changed dramatically since I watched it the second time.
After I watched it the first time I was bashing it for all its worth, but thats because when you come into a movie like that you have certain expectations, from the trailers, from the previous films and from the hype. So watching it the first time very few people get a true sense of the film for what it is. Thats why when you watch it the second time, more often you really come out understanding the film and being able to rate it for what it is.
There are a lot of powerful messages and powerful moments in this film, and it deserves a lot more credit than its given. I really think Bryan Singer did a great job, and even though I wish the costume's colors had been a bit brighter, Superman still shines through any imperfections for me.