I think configuring Cubase is about as simple as any of the other recording applications out there. The manual doesn't really contain any useful information...too bad about the trees that were cut down for it.
I just bought me a new Quadcore PC but so far I have used a pretty old computer. I am running Cubase with a MOTU interface however and the PCI card that connects between my interface and computer does a lot of the calculating.
For me Cubase has been a reliable tool to record sessions with up to 24 tracks at once. I never had to worry about the stability and if something wasn't working anymore it always was some other software or hardware.
I have been using Cubase for about five years now. Its biggest flaw is also its biggest asset: it simply has become to deep in functionality to be able to actually use it all. I don't care for the pitch shifting options too much and Steinberg could have given Cubase a function similar to Beat Detective without us having to do long editing.
Besides that Steinberg is really good about udpates and new content for registered customers.