Pros
The brightest and most passionate software professionals I have ever worked with. Thought leaders in all areas of software development. I learned more about software development in my first six months at ThoughtWorks than I had in the previous eight years of my career, and I continue to learn constantly from some of the best in the business.
Cons
Travel of 4-5 days a week should be expected (although I am currently on a local project). As consultants we are often hired by companies that need help, which means their existing processes don't line up well with ours (think Waterfall, Scrummerfall, or complete chaos). It is sometimes hard to be invested in the company when you spend all of your time at the client and don't get to spend much time at your local office.