I picked up one of these (and a mx310 for my laptop - which has horrible feet) last week - its about the same size as most current amphidextrous logitech mice. To me the buttons on buttons arn't that bad - the positioning means they stay out of the way most of the time for me, and i tend to use the extra buttons for things like copy-paste rather than regular things.
I don't really have anything good to compare it with but this mouse is *smooth*. I'm using it on a 15 year old computer desk (yes, i will be getting a mousepad, eventually) and it feels like its gliding on silk (more so than the previous logitech cheapie i was using, and the random temporary mice i get for free, and only use when things stop working fine). Personally, i rather like it.