Robert-
I flew OK on the AMS-PRG-AMS bit last December. I wasn't PM at the time, so I know nothing of courtesy upgrades, and I know nothing of their trans-Atlantic product, but overall, I was very happy with my experience. The FAs were polite, attentive, and *fast* (in < 1 hour, they served a beverage and breakfast to a completely packed 737.) Also, the check-in line at PRG wasn't quick, but I felt that it was average for a European airport.
FYI, I found the trip on DL metal to AMS then OK to PRG to work out *very* well.