I have a 2015 3500HD, I also get a ton of compliments on the looks. It is really a nice pickup. Any complaints I have are really minor, like someone else mentioned the layout of some of the controls are not intuitive at least to me. I have put like a million miles in several GMT900's so when the door unlock changes its location on the switch stack from bottom to top it bugs me. Overall though, the interior is outstanding in my opinion. The interior is stone quiet, everyone that rides in it, comments on how quiet they are. I pull the guts out of mine and have put 8k on it in the last 3 months, and zero reliability issues.
When the new high hp Duramax comes out in 17 I am buying another one.