Ventajas
The company is always willing to adapt and change on the fly to chase new growth initiatives which can make for a fun, exciting environment. The pace of work is fast and the organization is lean, flat structure. You will most likely have the chance to work directly with leadership on all of your projects and they will want to see the results of what you're doing. You also get to work with smaller teams than most companies so you will also probably be making quick decisions on the fly. The company is also has good flexibility if you need to be out of the office for something.
Desventajas
Depends by department and what you want out of a company, but it can be hard to develop strong work relationships and the office can be quiet sometimes. People are hard-working and the office is small, so it gets quiet quickly when people are busy and need to get things done.