Pros
The people there were great. I loved almost every single one of my coworkers, and made several very good friends during my time there that still remain today. The work hours, up to a point, were flexible. We could leave and come in whenever. Some people might take a longer lunch to go work out in the middle of the day, or have lunch with friends, and it wasn't a big deal (for the most part). The hours weren't closely monitored, so there was a lot of inherent trust there - you were expected to have worked 40 hours, and as long as your work was done that was the important part. I really liked the work I was doing. I got to work on some interesting projects, and most of the time we were building these from the ground up. That meant I didn't have to work with existing systems that were clunky or inefficient - we created the idea and built it. I learned more at this job than any job prior. So much of my work was trying new things or approaches, so I was able to learn pretty much every day. I had a personal stake in the company - my opinion was valued for the most part, and I could be a part of decision making despite me not being in a position that traditionally would make decisions. The company structure was flat - we were all allowed our say, and could discuss our opinions as equals.
Cons
The boss would constantly hamstring your decisions. There was absolutely zero process; we would agree on a plan to move forward with a project, then immediately the boss would change his mind and within 24 hours everybody would be on different pages again, because he'd go to individual people and change their priorities directly. If I had a quarter for every time the boss told me that <important thing we needed> was not in the budget right now (but was coming!), I'd be a billionaire and not have needed the job. Constantly, our calls for a project manager (to inject any sort of process) would be rebuffed. I think he thought that he was good enough - I recall him telling somebody that he would feel as if he was losing his connection with his employees if a project manager was in the middle. On a personal level, the boss is a compulsive liar and overall a terrible manager. As mentioned before, he would override processes and derail plans every single day. His obligation to change plans on the fly would infuriate us, as we would put in tons of work, only to have it invalidated. He would set work policies orally, then renege on them. Despite telling potential employees that we had flexible hours and the ability to work from home "whenever we wanted to", we were eventually just told that all work from home requests had to go through him, personally. I can think of countless other examples where his personality would derail our ability to work cohesively. On top of that, he took every single thing personally - if you were disagreeing with him beyond just a cursory disagreement, he would assume that you disagreed with him on a personal level, almost that you were spoiling for a fight. He would become very irate and shrill, making it immensely uncomfortable for the rest of us, despite us just giving our professional opinion on the matter. I feel this doesn't really sum up the cons well, and they come off as disjointed, but I feel that represents the company as a whole: disjointed, frustrated, unclear, and not a place you want to be. Stay far away - there's a very good chance everything will come crashing down very soon.