Pros
I worked for a subsidiary purchased by Fifth Third for three years, but we were considered Fifth Third employees. We did all their training, had access to the same resources, and were offered their same benefits. Benefits and 401k match were amazing, their ethics and compliance training actually demonstrated their efforts to care about all employees. I had issues with a boss acting somewhat unethically, and they immediately stepped in. I loved working here. There were so many other opportunities I could have moved to within the company, too - they prefer to hire from within first if they can. They also have a great long term business outlook, so I think they will do well for the long haul - and their employees will do well as a result.
Cons
It's corporate, so you can get lost in the shuffle, but that's not always a bad thing for introverts.