I've enjoyed the music scene and cheap rent, but have experienced major culture shock. It is a very intense place, full of contradiction, i.e. extremely open-minded in some areas and absurdly conservate in others. Berlin alternatively challenges and reaffirms one's various values.
Sometimes it seems like the 'adults' have left the city and left the 'kids' in charge. At other times, it feels impossible to breathe without violating some ponderous rule. Many are sucked into what is called a 'Berlinquency' - an existence in which one is spoilt by the hedonism, looseness, and condusiveness to self-obsession this place affords.
The tech scene is ok. There are a lot of clones. Some great meetups, though. It all seems to be on the up. Watch this space. And visit for a month before deciding to move here.