Pros
I worked at Selling Energy for about 3 years. It's a fast-paced work environment and management expects employees to be dedicated, flexible, and self-driven. As a relatively new and small company, I was required to wear many hats. For me, that was the biggest benefit of the job - no two days were the same, I got to tackle a wide variety of projects, and I gained insight into how a business can grow exponentially from the ground up. This company nurtured my entrepreneurial spirit, gave me the flexibility to take on projects that interested me, and supported my decision to pursue my own entrepreneurial ventures when the time came for me to make my next career move.
Cons
If you want coworkers, you need to be located in SF. I moved to LA shortly after I started, so I worked remotely (as did about half of the employees). We utilized GoToMeeting on a daily basis, but if you need people physically around you, then you'll want to work out of the SF office.