Pros
On the up side, Geisinger is a solid employer. Once you get in, if you are good at your job, you will have a job indefinitely (taking into account any major market changes). People were generally nice and they really care about patients and serving the community. Benefits were competitive. Also, for tech folks, very good work from home policy (at the time, and that was pre-COVID).
Cons
Teams tend to be stagnant. Doing a job well can work against you because you won't see much advancement. Promotions are hard won because they don't like to move staff around too much. Unless you self-advocate somewhat aggressively, you can find yourself working in the same dept, under the same manager, for quite a long time. Even if that manager is good, this can be bad for your future carrier because you don't get further experience and opportunity.