Let me start by saying that the whole company had a very big initiative to push for positive reviews. This included going after customers to write good reviews and also asking all the employees. So I would say take all the good reviews with a grain of salt.
Overall, from my experience I learned that the founders were pretty smart and cool people. They started something special and really believe in the vision. However being so young and in the pocket of VCs that funded them, they had to hire a few "experienced" people at the C level and as VP. Let me tell you, some of these people are either enormously incompetent, not having any idea what to do or are just devious and backstabbing. I honestly don't think the management cares about their employees one bit. They will give you a lot of empty promises and try to pump you up but have 0 loyalty to you.
The company always talks about being a "startup", but know that it's very hierarchical and they're trying to become more so. The leadership team just keep giving themselves new and higher titles every few months (along with I assume pay bumps), while the rest of the employees get nothing. They are also extremely secretive for some reason. They would keep things like moving a warehouse of capacity issues a complete secret from employees until the very last moment which created huge issues because sometimes customers would find out about this before the employees.
I personally had to quit as soon as I could and I am glad I did so. I highly doubt my job was in danger of being cut but they did lay off a huge part of their workforce recently using the COVID crisis as an excuse, even though their revenue was actually growing quite a lot.
P.S. you are also going to be severely underpaid.