Pros
Fast moving environment with ability to work under many hats with good personal and professional growth - just no financial growth. Some groups allow flexible schedules, and amongst all the stress, a fairly relaxed tone. There are some great people working there, but many have started leaving at a rapid pace. It's a good place for a short stay, but not good for long term.
Cons
The culture will eat away at your sole, and will slowly suck the life out of you. You will be expected to work ridiculous overtime without any extra compensation. If you're like me, you'll be commended for being a top performer, even awarded for it, but they'll always have an excuse as to why they can't offer you a market fair wage. Make sure you're well compensated walking through the door, or all you'll get are false promises of things to come in the future; nothing will ever come. They try to tout their policy for fair compensation based on ability and performance when they hire, but it's a big joke. As you're role exponentially expands in scope and complexity, they won't offer any fair wage adjustments. HR blames your management for the fair pay gap, while your management blames HR - it's a loop of BS. In the end, you'll be operating at an expert level, but kids right out of college will be making more than you answering phones. When you point out what a market fair wage is to your VP, and present legitimate data then ask why they can't offer it to you, they may respond with a suggestion to refinance your mortgage - that's what they said to me anyhow. If your role directly influences cost, as mine did, you can save the company millions of dollars annually, but you will never be offered anything for your hard work or dedication; there's no incentive to continue showing results. Meanwhile, you'll need to stomach the fact that the CEO is among the very top compensated in the state of Massachusetts every year. Furthermore, there's lots of uncertainty for the future, and lots of wonder if the doors will still be open when you show up tomorrow.