Pros
Working for CounterTack was a stimulating challenge, providing advanced endpoint security software solutions, using behavioral analysis, machine learning, and reputational techniques to address sophisticated malware threats using a massively scalable platform. Attacking hard problems at petascale. Not an easy job, but never boring. Some of the smartest and most talented folks I've ever worked with. They changed direction, and with very little seniority I was one of the many who didn't make the cut, but I'm not bitter about that -- it happens, and I learned a lot in my time there. Pays well if you have the chops to keep up.
Cons
The usual complaints about management shortsightedness. But more than that, a tendency to fall into the trap that many organizations are susceptible to -- getting too attached to an approach that probably just can't ever work. Looking back, I should have raised my voice about this earlier and more often. A lesson learned I guess.