There's a big range of clients and types of projects you can work on; there are tons of learning opportunities; there is a good amount of flexibility in work location and hours; and, most importantly..., the people I work with are supportive of me personally and professionally
Hours can be long because you'll have client-facing work as well as several EY-internal work duties. Some folks get "stuck" on a client (which can usually be resolved with assertive communication and... some idea of an alternative project). There is a huge emphasis on the "Path to Partner"... even if you are not interested in becoming a Partner (or even a Senior Manager). In line with that, there is also a big emphasis on sales, which can sometimes compete with focusing on the actual work.