I would say before one moves to Berlin, you should make sure you're alright with these:
- for a great part of the year, poor weather with very low cloudy skies
- winter darkness
- occasional hostility to foreigners (in certain neighborhoods, in words and sometimes with violence)
- high energy and telecommunication costs
- poor access to good vegetable/fruit quality
- terrible restaurant offers in certain styles (japanese for instance) ; in general lack of variety
- ugly city
Also be careful and do check about the compromises that some promises made come from. For instance the cheap housing is in general badly constructed, and your landlord will perform renovations so they can drastically increase your rent in later times.
Can't comment about the startup culture.