We've been hosting dedicated servers at RackSpace for years, and have always been happy. On occasion you get a mediocre response that frustrates you, but 97% of the time, they are off the charts.
They had an unexpected outage that affected a lot of their customers. Thankfully not us. They were awesome. They kept everyone informed as to what was going on, and issued lots of refunds when it was all said and done. Something to the tune of millions... And without people having to even ask. They then provided a detailed breakdown of what happened, how they fixed it, and how they were going to work hard to make it never happen again. I've never gotten that from any other hosting company!
No one is perfect, and they have their hiccups. Cloud servers is not for the faint of heart. You have to know what you are doing! All in all though, they treat their customers well, and they try very hard to make everyone happy! After almost 7 years. We're happy!