Pros
The smartest group of people I have ever had the opportunity to work with, at every level. The Company is led by a forward thinking, fast-paced CEO who is always on the go and is very passionate about the product and the industry. His dedication and enthusiasm empowers the employees to work hard and get on-board with the Company's vision. Great benefits, casual, laid back environment and the added perks always help (company events, snacks and drinks). The people are really what make the company such an awesome place to work - not only are they knowledgeable in their respective fields, but each person is always willing to help in any way they can and they all have a great time doing it. It's important to enjoy who you work with, but you feel like family when you come into the office.
Cons
Although not technically considered a start-up any more, the "work hard, play hard" mentality can be arduous at times so it's important to keep the jokes and relaxed atmosphere going to lighten the load. Being flexible is a necessity in this environment, as things change constantly - this can be a good or bad thing depending on who you are.