Penn has a very large non-traditional segment. I am the oldest in my class and can't say I have noticed any different treatment. I probably bring up my age more than anyone else.
I also think the students here are pretty amazing. I think the adcom has done a good job of getting a good mix of students and really good people at that. Seems to be a lot less drama here (compared to some programs), and a supportive one at that.
Penn is a bit of a traditional program and perhaps more resistant to change than some other schools. The faculty themselves complain about the difficulty of making any changes. They have slowly been adding more clinical time to 1st and 2nd years and doubt that trend will change whilst keeping a traditional lecture style. Attendance at lectures is (mostly) optional and lectures are all recorded(that is not the case at every school) which is a big plus for me.
I have mixed thoughts on the instructors.... it seems I pretty much like all of the instructors from the clinical side and have mixed feelings on the professors on the research side. Still, I doubt it is much different than any other place.