Admittedly, I had been spoiled by another trip to Germany. Berlin sustained so much damaged during the bombing in WWll that 90% of their buildings have been built since the 1950's, making it lot less charming (although probably much more efficient) than the medieval little towns that you still find all over Europe. Much of Berlin's history centers on WWll and the Cold War - The Berlin Wall, Check-point Charley, the bunkers, etc. which is interesting, but there wasn't a whole lot new for me. I do regret not going to the Jewish Museum there - I've heard it's great and takes a very through look at the past 2000 years, not just the WWll/ Holocaust period. Last trip we saw the Holocaust museum in Nuremberg - it really made an impression on me.
I'm sure Berlin is a much prettier city once the grass and trees green up. I think one of the greater draws is for the 20-30 something crowd - the night life is supposed to be terrific. When you snoozing by 10:30, though...
Here's a couple of shots of the Berlin Wall that still stands - it is now covered by artwork done in the 90's. Sorry the pics are so poor, they're through bus windows.