Well, I had a colleague who worked with them directly. He was a product manager who formerly managed incident response, and this was at a company that at one time had incidents that affected significant chunks of the Internet (no longer - that mantle has passed to AWS). It's been a couple years now, so the details are a bit fuzzy, but I remember him saying that dealing with Oracle was about the worst experience he had on the job. Their representatives were outright rude and condescending, and seemingly difficult to no purpose. So that's my (2nd hand) experience with them.
I'm a bit young to have ever known much about Sun, but I get the impression that they were very respected for their products and commitment to open source, and Oracle's purchase seems to have really rankled the community. Interestingly, the only Oracle products I use are all from the Sun era - MySQL, Java, Virtualbox, and ZFS.