Seeing as I now own two lenses with auto-focus and six without, I find I don't miss it at all and actually get pretty bad results with the piss-poor auto-focus I have. It took a month or two but manual focusing comes quite naturally now and I think it's something everyone should work on as it makes you step back and think more about your composition and layout. The only real advantage to auto-focus is with action stuff like sports or birds in flight.
I have an old focus screen in the mail right now that should help with my manual focusing. One thing that old SLRS have on new DSLRs is a good focusing screen. Seems that companies are trying to have people rely on the crutch of good (=expensive) auto-focus lenses because of their terrible focusing screens. Hopefully it's easy to install (I hear they are).