Pros
I wasnt looking for a new job when I met some of the folks from HookLogic a few years ago, but I liked the company and the team so much that I made the jump. I'm happy to say I don't regret it, I have learned so much and grown a ton in a short time. There is so much opportunity to learn and grow at a company of its size, and the technology is truly one of a kind. The clients really believe in the product and are huge supporters, which is very rewarding. Also some of the smaller perks (like annual company retreat) make the culture really awesome!
Cons
Cons are the same as they would be for any company with under 500 employees - the biggest one probably being that there isnt as much room to move within as there would be with a large global corporation.