Pros
Kaiser has great benefits, especially generous paid time off (vacation) and, depending on your location and union (if any), generous retirement plan. Also, judging from the incompetent idiots I work with, it appears that once you manage to actually land yourself a job you are pretty much guaranteed a job for life. I've never seen anyone fired, and that includes the incompetent f***-ups.
Cons
Kaiser treats their employees miserably. They have little sense of a proper work-life balance (their "Thrive" commercials are just a bunch of feel-good propaganda, if one judges by how they treat their paid staff). Also, if you are a performer and not a slacker, working at Kaiser can be kind of demoralizing when you see that the slackers never get reprimanded for their lack of ability or participation in the total work effort, and they get the same annual review rating and salary bump that you, the always achieving super performer, get.