Pros
You have the opportunity to work with incredibly talented people. For most positions the compensation is competitive. Benefits are great -- ERCOT provides a contribution of 10% of your salary to your 401K every pay period regardless of what you put in.
Cons
ERCOT is a quasi-government entity established by the Texas Legislature. It's not for profit and highly regulated by the Public Utility Commission (PUCT). These constraints undermine any attempt to recognize the need for change and respond unless mandated by the PUCT. Things move much slower than in the private sector and people stay in some positions much longer than they should. Just because you can't perform or in the wrong role is no reason to move you. A layoff in late 2010 appears to be solely to reach a magic number to satisfy the PUCT and now some areas are suffering as a result of limited resources.