Biggest con is going to, again, be tied to smaller companies. It is also something that some people may view as a pro, but I've seen several people struggle with it so I've decided to list it under the con side. Because this is a smaller company, you will often be asked to do things that you've never done before or may not be comfortable with. They will always be things that you have the skills for, but may be something that you've never done before.
I classify this as a con because it does force you out of your comfort zone. I know from hiring and managing dozens of people that even though people might say they like being pushed out of their comfort zone, that is rarely the case. For those though that embrace new horizons and are truly ready to take a leap into something you may not be comfortable with, this is an easy slam dunk.
The only other con I could really name is that there's no 401K matching. Not a huge deal for me and the compensation for roles, based on what I've seen in the market, makes up for that. But I want to be transparent.