I worked with them for over 4 years as an internal consultant, managing both B2B (customer) relationships and my own projects internally at our organization; they are professional accountants who take their work seriously but also have fun doing it! They always deliver great results to us without fail - that's why we kept working together so long time ago when other agencies were not delivering much value or even worse had issues like late submissions of reports etc., which was quite common from smaller vendors back then.
The only thing I would say is there should be more training options available since some new hires may need additional support during onboarding process due to lack of experience. We used them mostly because they delivered quality services every single day while others just failed miserably sometimes weeks/months after signing up contracts.