Hi peacedoc!
As the title of my post implies, I'm a former MUG-student. Presently I study in Sweden. I was at MUG for only 1 term(the first). I guess the teaching is pretty much the same as the rest of the world, with some exeptions(e.g. Sweden). The teaching is the usual, old, 'classic' way of teaching, where the lectures come to play a great role(far away from PBL).
Most of the professors are ok, but differ from the swedish, and probably also the american ones, in their tendency to be a bit arrogant. They demand a bit more respect and often bring out and remind you about the unequality that exists between them and the students. But most of them treat you good as long as you show them some respect.
I don't know if there is such possibilty for you US students(to have a 4 year). The best thing would be to contact them about that.
If I compare MUG with other polish universities, I wouldn't rank it the first. There are other universities in Poland with longer experience in teaching medicine in english. MUG has relatively little experience(4 years), they are probably the ones with the least experience. Krakow has longer experience, and I think better teaching and Krakow is a really beautiful city(most beautiful in Poland). So if I would choose again I definitely would choose Krakow. But it is harder to get admitted there. When I applied to Poland I didn't know so much about their universities, so I just choosed the closest one, which was Gdansk.