Terrible is relative. Never been to BER, but FRA is far better than similar-sized European/US airports like LHR or LAX (though a far cry from best like Changi, Chek Lap Kok or Dubai), and the smaller international airports like STR or FKB are quick to traverse and comparatively easy to access.

In my experience living in the most important city in the world the Berlin and Munich airports are a marvel of efficiency and comfort that I would kill to have back home.