I liked it. It wasn't the greatest superhero movie I've ever seen, but it certainly wasn't the worst.
I loved the little bits thrown as a nod to longtime Superman fans. I thought the actors did a fine job, especially Routh, who at times, seemed to channel Reeves. And the sequence with the plane was impressive. I didn't even mind the spoiler.
I think the main plot line failed miserably and I think it pulled what could've been a great movie apart. I think if you want to make an excellent, narrative driven movie with Superman, then you should. If you want to make a Superman does 'the greatest thing...ever' and saves the world movie, then you should. It takes a skilled hand to weave both those type of stories together. A skilled hand absent from Superman Returns.
By the way, my nephew, during the movie asked me where Superman put his cape when he's dressed up as Clark Kent. I was ashamed to admit that I didn't know. So, I made some half answer about folding it up and tucking it into his pants.