I was just in Budapest. It was really beautiful, but I encountered some of the rudest people I have ever met. I've read on other travel sites that people in Budapest are extremely rude to tourists compared to the rest of Hungary. Maybe it's implied by the nature of this thread that you should learn the language before you move there, but you definitely should for Budapest (assuming you don't want to encounter rudeness).
As a matter of fact, I do speak the language. A lot of things feel weird to me when I come to visit the city. I have this uneasy feeling about things like the Hungarian Guard [1][2] - a paramilitary group having a rally on the most most important square in Budapest. Or having a fascist party, as the 3rd biggest, in the Parliament [3].
Yet, there is an incredible amount of gifted people, who are the exact opposite of these jerks. I guess a lot of people here admire undertakings like Prezi, LogMeIn, ArchiCAD/Graphisoft, or Ustream, all coming from Budapest.
I moved to budapest years ago, rudeness has been getting worse super-linearly with the increase in tourism.
I understand and speak a bit of hungarian now and I keep getting worse service in bars/clubs/shops/restaurants than I got years ago as a broke exchange student speaking broken english.
EDIT:
mind you, I still think the city has a lot of pros, and could be a great place to live in cheaply while working on your project.
