When I got the offer, I interviewed the 6 teams from two product areas before I accepted the offer.

This is always good advice whether the offer is from Google or a Big Bank.

Talk to the manager, talk to your coworkers. Once they give you the offer, their job is to market the job to you. Use that as an opportunity to interview your future coworkers. When I was considering finance job, I've even gone as far as asking the future coworkers to implement different algorithms and/or talk about their system architecture. If it was too crazy, it was an immediate sign that I won't be happy there.