Pros
Working at C3 is a unique opportunity that I'd recommend for anyone who gets the chance: - Tackling an enormous market (economic) opportunity as well as important global problem; - Exceptionally senior management team, with access to the necessary resources (expertise, contacts, $) to successfully deliver on the opportunity; - A strong team across the organization, hard working but also good at having fun; - An opportunity to work with and learn from Tom Siebel, a legend in the enterprise software world. In addition, while compensation packages at hiring are decent, strong performance is quickly recognized in terms of both increased responsibility and much increased compensation. And yes, I am no longer at C3, but I left for non-C3 reasons and would be happy to come back if my situation changes. Net net, I very much enjoyed the work, loved the team, and would recommend the company highly.
Cons
Failure is not an option, and everyone is expected to consistently perform at an "A" level. If you aren't up for that challenge, this probably won't be a good fit.