Pros
Ernst & Young is a highly visible and generally respected organization in its industry space. Outsider perceptions are that it is a highly efficient, reliable, and ethical auditing house. Working for EY generally gives outsiders the perception that you are a highly competent professional. There are opportunities for flexibility in managing the work/life balance and some of the benefits are rather useful.
Cons
The current reorganization has left the IT Services organization in complete disarray, with the separate internal organizations fighting for turf at the management level to the point of malice. Many of the staff are in positions for which they are under-qualified and would be more useful in a role more suited to them. Hard work is rarely rewarded or even acknowledged, leading a lot of people to just try to remain unnoticed by doing the bare minimum - mostly administrative.