Pros
This is a training ground, this is your boot camp for a professional career, regardless of whether you went to college or not (which, if you didn't, is a God-send). An invaluable place to gain real-world experience. You may not be 100% ready for another role at a different company, but you'll be pretty close. Pay the price and enlist here if you're desperate. If you're an established professional who can line up other opportunities, I'd recommend avoiding this place.
Cons
Look, every company has its problems, and I'm not 100% sure how RMS stacks up against other companies, but boy oh boy, this place is on ONE of the circles of Hell. From my unknowledgeable perspective, it seems that there's a major disconnect between management and everything else. I've seen plenty of teams getting overworked because of bad business decisions, trainwreck decisions that keep me asking "when", not "if", will RMS collapse? The CIO is a really smart guy, super knowledgeable, but he's not a great administrator or high-level manager. So it's a pain to have to report to him, or have him as a stakeholder. And his wrath is to be feared, should you upset him, which is NOT conducive to a healthy work environment. From what I understand, the pay isn't great. There was a steady, unending stream of friends that left RMS for other positions that paid 10% - 50% more. I will grant that RMS's healthcare is pretty good, and if you're single, is free. However, that kind of insurance covers maybe 5k in yearly salary, which is still well below a decent pay.