I've noticed no speed differences between Lion and Snow Leopard... Really, it's all the interface paradigm changes that will bug you the most. As Amiga users we have 26 years of training in the old Deaktop model... Lion gets rid of things (optionally, but by default) that probably don't rely make sense, but we have grown used to.
It's a good upgrade, and while I think there are a number of missteps... It does show the future of the desk top... This Apple does, not by innovation but by simply having the balls to do it!
