Pros
The clients are top notch, and the people who work there are rock stars. Everyone seems to be on the same page and working towards the same goals, and are always driven. Selfishness is not something that people are about. Helping others to get the job done - whether working late or doing something that's not necessarily "in your job description" - is amazing. Plus the office in Chicago is really cool. There are great views of Lake Michigan and Michigan Avenue. Plus the location of the office is perfect...you can walk anywhere in the city within a few minutes.
Cons
Since everyone who works there is really good at their job you get some people who are a little full of themselves, but that is few and far between. Also, you're going to work really hard everyday and will be thinking on how to make everything that is being done better - so you always have to be on your toes, up on industry best practices, looking for cutting edge technology and always being one step ahead of other agencies. At DTAS, it's not just getting things done and out the door, it's about thinking things through and always being the best.