MacBook Air 13" Late 2010 Upper Case
I'm pretty experienced in dismantling/reassembling Aluminum MacBook Pros, plastic MacBooks, aluminum Powerbooks and various iBooks and this was not bad at all. Mostly just time-consuming.
I'm not sure I'd rate it as "difficult" for those with previous experience. The screw count is particularly low by comparison to other machines I've worked on, and there are only a few different types of screw.
The new top case arrived with the adhesives to re-secure the speakers, new screws to attach the trackpad, and the microphone was pre-installed.
Excellent guide, and a great help as always. Thanks!