Pros
You are never doing the same thing day in and day out. There is so much to do and so many areas to get involved that you feel extremely connected to the product and to the team. Your job here is what you make it. We all have titles, but the best part of my job is that if I see something that needs to be done, its up to me to step in and take initiative. We have a great culture here - we work hard but we also have fun doing it.
Cons
The startup word in general is sink or swim - if you are willing to put the work in and really take that initiative, there is an endless opportunity for growth here. it can be daunting to have a lot of control over your projects, but if thats the environment you excel in, it can also be incredibly rewarding.