Pros
Your fellow engineers are typically pretty good, although a lot of the absolute best talent has left by now. The office space is nice, and they have decent perks. Work is flexible and you can do things like WFH, take long lunches etc... Your direct boss is probably a pretty cool person. Cyanogen's talent pool is still highly regarded by other Employers, and time spent here won't look bad on a resume.
Cons
It's been run terribly up until now. I can't swear to the new CEO as I wasn't under him very long, but the previous one was a train wreck. Projects are typically high minded but low on the details needed to make them successful. Project management is the worst mixture of scrum-as-waterfall i've ever seen. This was improving slightly in that projects weren't being waterfall-ed quite as much (after the lay offs mostly), but that was replaced by almost immediately by a complete lack of direction.