Pros
The people at ERG are genuinely nice. The environment is friendly, and fellow colleagues are there to help you, not to compete with you. The work schedule is very flexible, and if need be you can work from home on occasion. There are some wonderful, considerate people, and the company strives to help you solve personal issues.
Cons
ERG's fantastic support for personal issues doesn't extend to professional issues. It is a challenge to get feedback from managers, even when prompted. This is mostly because they want to be nice, and make everyone feel comfortable, but it ultimately presents a challenge to personal development, and growth within the company. Furthermore, though ERG strives to build a strong community within the office, it's not an ideal place to build your social life outside of there. Employees for the most part have their social groups outside the office.