Not helpful, but accurate:
http://theoatmeal.com/blog/fix_computer
I installed it yesterday but haven't had a chance to play with it beyond a few clicks. Reverse scrolling took about 2 seconds to get used to on my MBP. I also find the Dashboard irritating in that you cant just get rid of it. Launchpad seems rather pointless unless you have forgotten what apps you have installed an feel like browsing through an iOS-esque tiled screen. Can't comment on battery life or performance yet.
Was surprised that the download what 3.75GB, but it appears that I suddenly have 10GB more free disk space since installing it.