The #1 worst part - most of the clients attracted to Taxhive are pretty new business owners and are novice to business, to taxes and bookkeeping. The clients are not very satisfying to work for. If you like the work and don't need the client interactions - you will probably like the quick turn around with Taxhive.
Typical big company bosses a little squeaky with money. Poor onboarding process, but that is only a week or so. Managers will be unavailable during tax deadline times. Company is constantly growing and chasing new staff, so it might feel understaffed and a bit disorganized much of the time. (Pro - you are part of the solution with your suggestions).