Pros
Please don't skip this if you are considering working here as an engineer. If you are good at what you do, realistically you can have a really easy job that does not involve working more than a few hours/day. You can use the rest of your time to upskill yourself in other areas, just hopefully for a potential different employer.
Cons
First, I'd advise you to look at the r/JPMorganChase reddit. The general sentiment of that thread reflects all I'd say here in greater detail, but... - Lack of opportunity to be compensated at a competitive rate to your peers (think ~30% lower on average). For context, when I left for a new job I got about a 50% bump in comp based on skill and experience. - Lack of opportunity to advance. On multiple occasions people I knew were turned down from promotions because "there are too many people at that level". Nepotism is rampant and extremely deep rooted. - Toxic culture. Just look at the reddit thread. You aren't an employee, you aren't even a number to them. You are simply a collection of metrics an an attendance count. - Betting on the wrong things. I get that the commercial real estate market benefits from full RTO, but the fact of the matter is that the company and working environment tends to falter when you take away the one thing that was keeping most of your decent talent in house. - Overall entrapment: you will spend your time learning internal tools that not only cannot translate to helping you work elsewhere, they will actively contribute to you falling behind your peers in industry. It's an clever but detrimental way to retain personnel if you ask me. Learn how to actually promote based on merit, and push back against terrible decisions. The people at the top are just people too, and in many cases they aren't as well informed about a given situation as you are, and therefore incapable of making the optimal choice given the circumstances. An org of this size should be able to run itself, but competent people are simply cowed by the arbitrary decisions of other people with fancy titles next to their names.