I was just at ADP. I flew an Archer and a Seneca. Maintenance seemed pretty solid. Aircraft have any squawks and their resolution logged in the aircraft binder. Stuff gets fixed or placarded inop (91.213) providing someone reports it.
I've heard mixed reports of ADP, but the place seemed pretty good overall, to me.
As many people have reported the aircraft may look a bit scruffy, but they are maintained and inspected at 100 hour intervals. In fact quite a few of the singles actually looked pretty smart. (If you are used to school 172's from the 70's).
As a disclaimer, I had a bad glideslope, and an inop trim indicator in a seneca. Note that any dual out there is charged at $40 which is highish for the US.