Pros: The cleanup. That's about the only thing about the SEs that I liked. That and Cloud City being more open was a nice touch. I kind of liked the additional Bigg's scene, but I also agree that he shouldn't have been introduced at that point. It adds a little to his character, but not enough that anyone besides a core fan (reads the books and all that) will care anymore about him. Luke's scream at the end of ESB was tolerable but unnecessary (I always felt he was at peace when he let go). I do like the new end song in ROTJ, but Yub Nub is still my favorite.
Any other changes after the 1997 SEs were completely unnecessary.