Pros
This is my third San Francisco-area startup company. My first was sold to Novell, the second was sold to Macromedia. I thought I understood how successful startups are run. Glassdoor sets a new standard. These guys really know what they're doing, and understand what makes a company successful. I've learned new ways of thinking here, not just about coding, but also by watching our CEO and the VP of Marketing. They do things I would never have thought of doing. (This is the first marketing person for whom I've ever felt any respect!) Any startup is a gamble, but working with these guys gives me a lot of confidence that we will succeed. Both the CEO and VP of Engineering value individual contributors and creativity, and will let you know it. If you just want to code, and do it well, you'll be appreciated for that. The quality of our work life is great. The company is headquartered in beautiful Sausalito, California. Our offices are a block from the water, and 1/2 mile from kayak rentals. We can watch the fog come in over the mountains. On Friday afternoons we open beer and wine and sip while working at our desks and listening to music, which we all take turns D.J.'ing off an iPod. While it's a bit of a jock atmosphere, the company is gay-friendly. (We're just north of San Francisco, after all.)
Kontras
Since this is a small company, there is limited opportunity to learn from your colleagues... If you're not comfortable going out and doing some research, you probably won't fit in here. Likewise, you need to be fairly self-directed. Everyone has to be willing to step into different roles, if necessary, so you might end up doing something onerous like PERL scripting, but these kinds of things are always temporary. On occasion, you'll put in long hours. (I've put in a lot of 10-hour days, and occasionally a 12-hour day.) These are voluntary, and I've never seen anyone pressured to work late. People just understand that hard work now will (hopefully) lead to compensatory rewards later. The company is currently a boy's club, and needs some female employees desperately. (I think that everyone realizes we need more balance.) I'm hoping that a year from now this will no longer be the case.