Not necessarily cons, but things to be aware of...
It's definitely challenging. It's a growing company, so you may be asked to wear a few different hats balance a variety things, and try new things. For some, that's a welcome challenge, for others, maybe not so much. Things move very fast here, and if you can't adapt and keep up, you may struggle.
Since you get a lot of ownership over your work, you'll definitely be held accountable if the results aren't there. If you thrive in high-pressure environments, you'll do very well. If you need constant confirmation and management, it might be tough for you.
If you're looking for a normal 9-5 where you can sort of "coast" through your day and leave your work at the office and not think about it at home, it might not be a good fit. And for the record, there's nothing wrong with that, but there are lofty goals here.