just upgraded from snow leopard to lion on my mid2010 MacBook (2.4 GHz Core2Duo, 4 GB RAM). So far, so good, no real speed increases or decreases, except for Safari seems faster. One complaint, this may seem as nitpicking, is the two startup screens with different shades of gray. during startup, there's an initial gray apple screen (snow leopard?), then just before the desktop comes up, it flickers to another startup screen thats a different shade (lion?). Its obviously just a visual detail, but it reminds me of something Microsoft would do with a Windows upgrade, i.e. unpolished. It makes me feel like my computers more outdated than it is. I enjoy all-that-is-Apple for their attention to detail. Would this be because my original BIOS was created with Snow Leopard? I remember my old PowerBook G4 doing something similar after I upgraded to Leopard.