The stock focusing screens in most cameras make it impossible to actually see the focus plane, even if you can occasionally get a hint of what's in focus. I use an aftermarket screen from focusingscreen.com, and it's awesome. My 2 most used lenses are manual focus only, and using the screen it's not a problem at all. I will note though that my 85mm 1.8 was not designed to be focused manually.... it's got a focusing ring, but it's almost impossible to manipulate it accurately since it has an extremely short angle of rotation, and less than perfect manufacturing tolerances. So, I guess what I'm trying to say is manually focusing with ease is a combination of the lens and the focusing screen. (and practice! lots of practice...)
Glad to see someone happy with FocusingScreen.com.. I knew about them, and have considered some of their screens. I was hesitant though.. as their website seemed a little hokey.
They're certainly hokey, but the product is great. The instructions and all that were badly translated and badly copied. The company as a whole doesn't have much interaction with their customers, the whole thing felt very hands off. But you do get an excellent screen at half the price of katzeye...
Now that I know what's possible I'd like to try a simpler screen from a different company probably. I think the one I'm using is a K3 style, it's got a split prism, surrounded by a microsprism ring, surrounded by a coarse matte. I'm curious what it might be like to use a simple high quality coarse matte without all the prisms. It's nice having a lot of tools, but they're also obtrusive when you're trying to think about composition.