I've been watching the show for years now. I love the music, I love the dancing (well, usually), and I enjoy watching the contestants gradually improve on their dancing abilities...or at least try to! It's a shame that the majority of the contestants are either has-beens or never-weres. Tom Bergeron introducing the "celebrities" never fails to get a chuckle from me. The show would be a lot less laughable if they used normal people as contestants. They would at least avoid the prima donnas like Michael Bolton, who demanded an apology a few seasoms ago after Bruno brutally but honestly slammed his dance.
There's one other thing they should change: audience participation. I'd much rather see the judges' scores being kept a secret until the eliminations, rather than place emphasis on votes from the viewers. It is a dance competition, and allowing the audience a say in the show creates the risk of it becoming more of a popularity contest.