Pros
The people. Young, talented group of visual effects professionals who liked to work hard and play hard. It was a young company who was excited to be working on the Matrix sequels and be part of a startup vfx company. For a while there was a communal feeling that we were part of something special that competed with the likes of ILM and Weta. In fact, most if not all ex-ESC employees are current leaders in the VFX industry who have gone on to bigger and better things. VERY TALENTED core group of people and to this day, ESC is good on the resume.
Cons
The hours were horrible, working 90+ hour weeks, 7 days for months on end. We also had to deal with the startup studio syndrome with little or no pipeline (at first) which made it very difficult to be productive. Some of the supervisors were also very condescending and negative towards the employees. A lot of egotistcal and big headed people running the place. To be fair though, the place had a wild, fraternity type of feeling so no one took anything (negative or otherwise) too seriously.