Vantaggi
+ Fast paced environment. Requirements can come quick when a new client onboards, and that is happening more and more often as the company grows. There are not a lot of dull moments. + Small team with very little bureaucracy. Things that need to get done can just be done without the need to go through a lot of overbearing process. The processes that do exist can also evolve if they aren't working out. + Technically challenging problems, with a lot of potential to learn. The product grows very fast, which means there is a lot of opportunity to learn about new technologies and apply it in a real-world setting. + Mature leadership that doesn't burn people out. Both co-founders encourage vacations. There are no constant death marches. The back-to-hybrid process has been very well-handled. + Friendly people and non-toxic culture.
Svantaggi
In the end, this is a start-up. There are going to be smart and capable people who see the above list of pros and say "no thanks." If you aren't a self-starter or require a lot of direction, you may want to consider joining at a later stage.