Rapid changes and expansion have, as others have mentioned, led to some questionable hires/placement
Reactive staffing has led to imbalanced workloads (saw this in another review and agree wholeheartedly)
Also as a result of the rapid growth/expansion/evolution, processes often change faster then they can be completely implemented leading to poorly defined/communicated directives
Benefits seem to be slowly whittling away - PTO policy changing to be more restrictive as well as losing a day in the upcoming year, 401k plan becoming less attractive, health premiums going up (although that's not entirely at the hands of the company)