Pros
I hadn't worked in a start-up environment before, so I guess that was a pro, to get that experience? I met some cool people. They pay well, or I got paid well. Unless it's around that big conference they have every year or some project that's been mismanaged (all of them) the work life balance is pretty good.
Cons
A bunch of people running around like chickens with their heads cut off, spewing uneducated opinions (not saying the people are uneducated - quite the contrary - just saying they all love to give opinions on things they know nothing about instead of the things they do know something about), fighting about everything, making meetings for everything but still not getting anything done and missing the mark by a mile. It's like the D-List crowd acting like the A-List crowd...but they aren't. And they're not fooling anybody but themselves. However, there are A-List people who do work there but those gems don't last very long. Also, the main reason for anything you're ever working on will never be shared with you so you'll never get the full picture of what you're working on because it's all a bunch of ploys, smoke and mirrors, and business moves, that again, I guess you're not supposed to know so good luck doing your job fully and missing half of the info you'll ever need to do a great job at it.