Working at a small, fast-growing company is not for the faint-hearted. Some days are long or really intense, and workload tends to be pretty heavy. You have to be very smart, nimble-minded, and focused to juggle all your responsibilities. There's no precedent for some decisions because the company is often on the leading edge of the industry. The amount and pace of change can be high. It's all normal for a company of this type, at this stage of its development. But for folks who require a high level of consistency or certainty, it may be too stressful.
Depending on how people want to advance their careers, or what skills they want to learn, the small size of the company may limit those opportunities.