We liked the Habel quite a lot. It is pricy, but we found it worth the money.
Asparagus is the thing here. Indeed, much of the menu involves ordering large amounts of asparagus to which a side of meat could be added. Curious for Americans.
They have a limited list of entrees, but the portions are large and the food is good. My wife was very impressed with the asparagus risotto with duck breast, and I had an excellent wiener schnitzel. The chocolate mousse we had for desert was the only disappointing aspect of the meal.
They have an impressive wine list for a German restaurant, and the service was efficient and helpful. You could certainly do worse in Berlin.