It's hard, really hard, but the trade off was worth it for awesome people, learning opportunities and to have an impact
Pros
The people - some of the most intelligent and brilliant people I have had the pleasure to come across. Flexible hierarchy - there's management of course, but their seniority isn't solely based on tenure, so if they are wrong you can challenge that. Also in most roles there is interaction across management levels, they are not locked away behind a glass screen. Changing environment - There is space to make things better, new challenges are around every corner meaning life doesn't get dull and you can gain experience in different areas. You learn a lot quickly. Opportunity and trust - if you have an idea to make things better, provided you have proven yourself and can hold your stuff together, knock yourself out. If you are complaining something is broken then you really should be trying to fix it.
Cons
It can be stressful, not necessarily true for every role but it's quite common, this is because: It's emotional- being a business where the co-founders are closely involved and people care is great, however it can also result in responses which are emotional which results in more stress. Sometimes it's a little chaotic - a product of a lot of the things I see as benefits There has historically been lack of other experienced individuals, which means sometimes you'd shoot for the moon, not even realising it was an unreasonable or foolish ambition. This is something they have worked on quite a lot and were getting better at in many areas.