Avantages
Modern office setting, "start up" feel, great location
Get to use latest technology, access to whatever tools you might need
Unlimited vacation/sick time
Free drinks and coffee are a nice touch
Leadership training
Ability to (mostly) make your own decisions and use best judgement
Very little meetings
Growth opportunities are there if you stick around, if not, it's a fair stepping stone to the next place
Inconvénients
No communication, everything is secretive, no transparency
Since everyone (mostly) makes their own decisions, there is no general schedule of when things are needed or completed, no official project launches, etc.
Leadership training is intense and isn't everyone's cup of tea (it's presented as optional), but if you decline you are singled out and treated differently.
Even though there is unlimited PTO, the expectation is that you never use it. I was literally told to try and never take a vacation on my first day. Basically you are married to this place, and family/personal life comes second.
CEO is not exactly approachable, have to choose your words very carefully.
Turnover is very high