Typical cons of working for any consulting firm; unknown and typically longer commute times, complex and challenging work with tight deadlines, higher standards expected of your work product, work assignments can vary greatly sometimes interesting roles but other times staff augmentation.
I love consulting! I love the variety and the challenges of my role, but it can be tough. Clients will typically blame the consulting firm before taking any responsibility, but most consultants are professional enough to take it on the chin and move forward.
It's a tough job but I get to work with some amazing people at Slalom which makes it all worthwhile. If I wanted an easy job I would have been frightened away by the challenges of consulting long ago.