Can't speak for UPenn, but UDM has many pros and a few cons
Pros:
UDM just moved to a new facility w/all new technology last year
UDM is in an urban area and never runs short of patients
UDM students do not have to fight for chair time or share proceedures.
UDM's facilty is caring and committed to student success
UDM students are highly ranked in overall NERB scores
UDM students typically are cooperative as opposed to competitive w/each other (per current students)
UDM dental school is a stand alone facility, it is not on the UDM campus, therefore parking is plentiful & free
UDM dental school is right off the freeway, easy to get to
Cons:
Area is a bit rough, you'll most likely want to live in surrounding suburbs (can make the trip in appx. 30 mins)
Weather in MI during the winter is not great if you are used to year round warm weather
Cost - private school
That's my two cents.