This is a pretty good article. Basically more personal and professional issues (i.e. coming out as gay and backstage drama with Isaiah Washington saying some homophobic things as well as feeling like he wasn't getting enough material from Shonda).
I also saw George's funeral episode at the gym last night. Even with the sound off, it reminded me how good this show used to be and also how many main characters are either gone or dead (George, Izzy, Cristina, Callie, Mark, Lexie, Derek, etc.)