Pros
There is a lot of upside to working for a startup, I know because I've worked for several. But I've also worked half my career at major global enterprises having over 100,000 employees, so I know first hand there is a big different. At a startup you have opportunity to grow and learn in your career at an accelerated pace. There are very few guardrails and you really can (and are often needed) to go outside your lane to help others and to get things done. At a startup you must be self-motivated, inquisitive, and ready learn things that you would likely never get to learn working for an enterprise. Working for a startup is like riding a roller coaster. Working for an enterprise is like riding a carousel. One ride is not "better" than the other, they are simply different. A startup can literally go out of business tomorrow, or it can pay you big $$$ through IPO or acquisition. Success of the company (and your personal success) is 100% dependent upon the individual contribution of every employee. It's very cause and effect.
Cons
If you need a lot of infrastructure support in order for you to "succeed at your job" then this startup is not the right place for you. If you need there to be "formal training" to teach you the companies technology then this startup is not the right place for you. If you can't catch and get behind the "vision" for how this startup is proposing to disrupt the industry, then this is not the right place for you. I have read ALL of the interviews and company reviews, the complaints, the slander, the disgruntled venting, and if I take a step back and take them all in as a whole, what I see are a bunch of people who DO NOT belong on a roller coaster ride and who DO NOT belong at this startup (or any startup), they need to get onto a carousel and focus their careers working for a corporations e.g. companies who count their employees by the thousands, not by the tens or hundreds.