I really didn't care for what they did to Debs character from s4-s6.
In s1-3 she was this no tough, sort of independant woman, who was very likable and although she made some pretty horrible mistakes, she realized them and was trying to fix them.
s4 wasn't so bad... She was a little loony, but that was from the pills etc... But some of the crap they had her do (Trying to get Haley to go to the shooting range with her, etc...) was completely OOC. And I don't even want to start with s5-s6. They turned her into this bimbo, who pretty much just irritated the hell out of me.