Vantaggi
Brand value definitely is the top pro(for this reason alone you can take OFSS over other noname company paying say 1-2 lakh more). If you are lucky you might get good work(spring-boot/microservices). what they quote is what you get in hand. Good worklife balance especially for developers. Job security. Perfect company for retirement. Overtime pay is there. Good people mostly.
Svantaggi
The chance that you will end up with legacy software written in PL/SQL. I did. (If that is the case then use your brand value and skills to get out within a year or so, or if you plan on staying do change your team). Pay is not competitive, even if you compare with Oracle India, OFSS in my time payed around 2-3 lakhs lesser, though if you are from IIT you can get packages above 15 lpa. For developers bonus is not timely, stocks are not given though you can opt for oracle ESPP. Consultants get timely bonus but their base pay is lesser. Also consultants have more work load. I had even heard of dry promotions, you get promoted without a hike. One guy I knew was also in same position for 5 years, higher management was not ready for his promotion due to his role being lesser even though he was a developer.