Just left BTS (2014) - incredible experience for the past 3.5 years
Pros
BTS is an incredibly exciting place to work, and actually a true meritocracy. Entering the company as a 22 year old that didn't know anything, I had tremendous mentors along the way to teach me everything I needed to know. There is a culture of challenging people to do great work, and providing coaching along the way. BTS has some great leaders and I honestly expect them to do great things. Lastly - the culture and people there are incredible! Everyone talks about freedom and responsibility, but BTS truly offers that. There is a culture of respect for people's lives, and the leadership embraces/lives the values.
Cons
For full disclosure - I did leave the organization, but only because I wanted a career change, not because of anything I didn't like there. The only thing that was slightly difficult during my time there was the work-life balance. But I don't think its any more than a typical consulting company. Traveling will be a part of the job, and it really just depends on the person. I loved the pace initially, but everyone is different and timing is important to consider as well. The good thing is, as long as you bring it up with management, they are very respectful of that and will work around to help accommodate your life.