The fast-paced nature means there can be long hours and challenging periods. The environment is not for everyone, and it requires being proactive about managing your time and energy.
As with any startup serving large customers, there's a constant juggling of priorities. Acknowledging this can make the review seem more credible and balanced. And if a customer complains about you - you're toast. Management always takes customer's side. This seems to be the biggest problem with people who get fired.
Room for process improvement: As the company scales, there's a constant need to refine processes. This is an ongoing effort, and it's a work in progress.