It's a growth stage start-up so can sometimes feel a little chaotic, but if you've worked at other early-stage start-ups you know that that's normal and necessary to move fast enough to succeed.
I don't find this to be a con, but expectations are high - this is a performance-driven culture, which is not for everyone. If you're excited about the prospect of challenging and improving yourself amongst a group of fun, smart and driven individuals then this is a wonderful place to work and learn! If you tend to care less about your work or are looking to coast, then I would look elsewhere.