Pros
Great place for your first "real" job out of college - you'll learn the ins and outs of corporate life and develop professionally. You'll become a low-key Excel wiz if you're in the right roles and you might make a few friends in the process. Bonuses can be wildly rewarding as you move up the ladder.
Cons
Base pay is garbage compared to industry standards and those discretionary/"black-box" bonuses that can be so wildly rewarding are basically used to keep you hostage. It's a super niche business which can make it complicated to transfer into the world beyond Calpine once you decide you've had enough. Despite the inclusive, flexible, fair, and open culture they try to convince everyone they're cultivating, they are firmly stuck in the past. Double standards and nepotism run rampant and once you see the extent of it, it becomes hard to tolerate. HR was never stellar at the local office but the folks at corporate who you'll be transferred to for basically everything are truly terrible - don't ever think they have your best interest in mind.