Avantages
The company is growing incredibly fast and the day-to-day is an adrenaline rush. I have high hopes for the company and couldn't be more satisfied with my decision to join. I left a great company on a similar growth trajectory, but joined a bit late in the game than I would have liked. The size, momentum, level of responsibility is exactly what I've been looking for. The culture is open, friendly, and collaborative. Walking in, you would be unable to tell who is what level of seniority. The company has been able to keep the hierarchy extraordinary flat. Lunch and dinner is catered 5 days a week. Benefits, perks, options, and salary are top of market. I have a ton of autonomy and have not had one instance since I've joined where I was feeling micro-managed. Overall, amazing place to work. I'm surprised the company (from a cultural standpoint) has been kept under the radar.
Inconvénients
Don't expect any hand-holding. Some formal product training would have been nice. You'll need to use the people around you to get ramped up. Find people at the company who can teach you what you need to learn and schedule a meeting with him or her. If you don't assert yourself a bit, you'll likely fall behind.