The performance of the product is very good. Given the transactional nature of the system one of the key focus areas for IT is to make sure performance is not affected for internal reasons. This can also depend on the server configuration and setup. For example, performance on Exadata machine is far superior to other Linux custom systems that companies choose to deploy.
In general though, as already pointed out, the platform is now very stable and has few bugs. Whenever there are any issues, the cause is usually customizations that we have made to the platform, rather than out-of-the-box standard functionality.