Pros
A small company making a big effort to grow into a bigger one, it is doing all of the right things to make that happen. It has been at it long enough that a lot of the dumb startup problems have been solved, yet still small and informal enough that someone with a little bit of self-start and ability to work independently can jump in and make a difference.
Cons
Does not have the structure of an older, mature company operating at enterprise level. Not for a person who wants to have everything about their job spelled out clearly in advance.