Pros
Saw another review on here that said TASC was a great place to grow as a junior employee, and I couldn't agree more! Because it's such a small firm, you get really wonderful exposure to the higher ups, who are experts in the field. Very helpful mentorship and foundational PR skill sets learned, lots of client face time. I still stay in touch with my mentor from this organization.
Cons
There's difficulties with small firms and difficulties with big firms - often one has what the other is lacking, so it just depends on what you're looking for and the stage of career you are in. TASC only had the traditional challenges of a small firm (scrappy, could be a lot of work and all hands on deck situations). But there weren't overwhelming cons, IMO, and the positives outweighed it.