I have been working at ITG full-time (Less than a year)
The culture is great, management is willing to help you learn, they offer wellness events for employees, hold many charity events.
Multi-timezone teams make for slightly troublesome communication, large company means sometimes depending on other teams to complete work before being able to continue on your own.
Advice to Management
Allow developers to be innovative and make mistakes, that is the best way to learn to do something without inhibiting creativity.
I applied through college or university. The process took 4+ weeks. I interviewed at ITG (New York, NY).
On campus interview, 2 consecutive Skype interviews, and one final Skype interview. Very nice employees, and helpful HR. Interviews were pretty easy and mostly behavioral questions. Great place for growth and work/life balance.