I lived in Berlin for 3 years, but I didn't found or form a company. I do have a friend who has just done it. I wouldn't want to comment on the specifics but the basics are this.

1. Very easy to form a company in Germany as a foreigner 2. You will need a native german speaker, it's beauracratic and you need to speak solid German to deal with it. 3. Taxes are higher than the US, but they are fair. You pay more as you earn more. 4. There are many taxes as an individual you can claim back, such as clothes, travel to work, space in your house etc. If you get a good accountant they can really help. 5. Berlin itself is very cheap to get a great location, good tech talent but not overflowing, incredibly decent lifestyle, lots of space, lovely place to live a chilled out vibe.

I'd say if you've lived in Germany and Berlin and like it, you can do it. If you have never lived there you should move their first and see if you like the German way of life first, it's not like US or UK.