Pros
Generally, the environment is probably one of the most relaxed I've ever worked at. People are usually keen to help you out, there's a lot of flexibility with starting/leaving times (although there are standups/client meetings in the mornings) and it's no drama if you want to work from home.
Cons
The company does have a very unyielding frame of mind around the company's philosophy of "self-organization", to the point of being extremely hostile to points of view that diverge from it, and by lines of questioning that try to point out the flaws and limitations of this system. Is it awesome not to have a hierarchy and people breathing down your neck? Absolutely. Is it horrible to not have someone to have a final say when it comes to decision making? Also very true. I've seen cases of conference expenses taking two weeks to approve, because people will tell you you need to own the decision and the process, but will give you zero resources insofar as who you can/should contact to help you out, what's the reasonable expense limit for the trip/expense, etc. You'll be regarded in a very bad light if you try to argue that sometimes you just need things to happen, that you have other work pending, or really that you're really not feeling comfortable around organizing a massive expense, envolving multiple people, and the pressure of a bad decision being made being squarely on you. Maybe the worst part, and a massive red flag, was the indoctrination session they make you go through on their philosophy, where they basically get you in a room with a bunch of other recent hires and try to feed you the self organization, teal tier org shpiel. At the time I was very enthusiastic about working there and the awesome work environment and coworkers I had, and I left that session feeling rattled and that the company had just attempted to brainwash me, like their version of a military bootcamp, trying to get you in line with the company's views. Their intention is probably totally different, but the vibe of the session was a bit strange. And again, arguments against their line were quickly dismissed. Generally I feel this blind focus on this philosophy hinders them in the end, and not acknowledging drawbacks prevented improvements being made while I was at the company. Not having a hierarchy is good, but sometimes having a semblance of a decision making entity is good and prevents chaos and time being wasted.