Story time: in college, I played a lot of the Team Fortress 2 beta. When the release came around, performance tanked. Absolutely went straight to hell. Annoyed, I fired a snippy email off to Gabe. Not impolite, but snippy, something around "I expect performance regressions like this out of companies less awesome than Valve." The next day, a senior engineer at Valve reached out to me, we hopped on Skype, played a few rounds with a bunch of Valve employees, and we monitored my system perf. A few days later, I got an email, "next patch should help you out, let me know if not"--happy as a clam afterwards.
These days I have more than a few beefs with Steam, but that sort of reaction sticks, and generates a lot of goodwill.