Pros
The people I worked with were awesome. It was a fantastic environment that supported anything you wanted to do, until the parent company came... leading to the slow, abusive and politically driven death of an entire office.
Cons
There were never any opportunities for advancement. US East coast office had great work/life balance. Sofia office expects you to work till it hurts. Company is mired with politics. Upper management humiliated, abused and threw people under the bus during development. When things went well, they took all the credit. Arrogant, many internal conversations belittling competitor efforts. Nothing is ever thought through, they live up to their name -- code reviews, commits, bug fixes and new features, all chaos... If your opinion is not in line with theirs, you are "not the best" and don't belong there. Highest turnover rate I've seen in any company to date. Shut down the US East coast office. Got the 'thanks for making us millions, we're firing all of you.' Spoke to many people in the Sofia office, they feel the same way -- just no one ever speaks out about it over there. Worst part was, the CEO actually allowed all this to transpire and turned the other way. Now people with families and their kids are in a very unpleasant situation.