Vantaggi
Well if you work in audit, you get to work with many people your age. That's a plus. Other than the company's status as a big 4, i would say that's the only plus. Salaries and bonuses very much in line with the other big 4 in Singapore.
Svantaggi
Disclaimer: I speak only for the Singapore office. EY offices in other countries might be run differently. - The TOIL (time off in lieu) system is a LIE. The only people who get to use their TOIL hours are those who perform very badly and hence have no engagements willing to take them up. They impose extremely strict requirements on TOIL usage (if you're a Singaporean, think "a million times worse than CPF"), so I left the company with almost 400 unutilised hours. - In my dept (external audit), many Singaporean managers have quit due to the high work load. EY SG has responded by hiring a lot of foreigners, many of whom do not have requisite knowledge. As a result, more work gets pushed down to the seniors, who are overworked and have no non-peak period to speak of. - Bonuses are bad (2-3 months), but then all big 4 are about the same