Pros
Made some great friends. Generally speaking my boss did not micro manage and my hours were flexible if I had an appt or something. Not all teams get the same flexibility though. It is 100% dependent on your direct manager. I rarely worked more than 40 hours but that's because I set boundaries. There are many people who don't and will work 60+ hours a week. So as long as you are able to maintain boundaries you can keep to the 40 hours.
Cons
So many problems - forcing everyone to go back to the office even though there are so many teams that have no reason or need to. Forced people to move to NJ and fired them when they said no. There are NO bonuses and yearly raises don't even cover a cost of living increase. Tenured employees seem to have a chip on their shoulder and can be very rude to newer people. Management acts like they want your feedback and will consider it but then they NEVER do anything to change or implement the feedback. Processes are archaic. Fiserv keeps buying up other companies but never actually merges them into fiserv architecture or processes so it is incredibly difficult to remember how you have to interact with all the different teams. Also, they treat unvaccinated employees like they are lepers. Senior managers were going to come to Ohio and have a big get together except they let it slip that they only invited the vaccinated. There is a reason that so many people are leaving and a lot of them have been with fiserv for 20 years or more. Honestly, so many cons I could go on for days.