Extremely steep learning curve;
Nasty, demanding, and unreasonable clients;
There are many friendly, approachable managers and partners, but conversely, there are equally many managers and partners who are fierce and who have no qualms scolding you in front of everyone in the office. It depends on your luck which managers pick you for their engagements;
Never-ending workload - although officially you are only booked for an engagement for a period of time, you will definitely have to work on that engagement after the booked period. And you are discouraged from charging the time-cost of that engagement after the booked period. You can request your managers to book extra periods for you to finish the engagement. However, your managers may question your efficiency and ask why you can't finish within the booked period, etc.; and
Their employee benefits and salaries are incomparable to those of Big 4 firms and other companies.
Advice to prospective employees, the nature of the audit industry is that of a fast-paced, demanding, and stressful one. To thrive in audit, you really need to have good stress management, project management, EQ, and grit. Expect to work with demanding, unreasonable clients and sometimes difficult personalities (of managers and partners). Expect to work overtime frequently because, in most engagements, the audit timeline is very short. You will have a rude awakening if you don't have the resolve to endure the above.