I'll admit that my intense dislike for 8 is solely based on aesthetics, since I've honestly never used it myself, but I take one look at that Metro start screen and just think...my God, that is hideous. The completely-flat rectangles that waste massive amounts of screen real estate, the color scheme that looks like someone shut their eyes and stabbed their finger at random on a palette...it looks for all the world like Babby's First OS, and I want absolutely no part of it. Most of us have been using the Start Menu since 1995; it works just fine, and over the years it's received incremental improvements that let it work even better. So why in all the nine hells was there any need to toss it out completely in favor of that monstrosity?
Honestly, it feels like there's this bigger trend among a lot of developers to make drastic UI changes mostly for the sake of corresponding to some perceived sense of "modernity," as opposed to whether or not said changes are actually necessary or desirable. The biggest personal offender for me has been Firefox; its most recent default appearance changes (along with the hyper-fast update schedule) make it clear that it's trying its very hardest to be as much like Chrome as possible. But here's the thing: if I wanted something that looked like Chrome, I'd go and ****ing download Chrome. I've done my very best to keep things looking as much like the classic FF3 layout as possible: the separate stop/refresh and home buttons all in a row, tabs on the bottom where they belong, the classic menu bar, the whole enchilada. I know I could theoretically do the same with 8, but I shouldn't have to download third-party external mods to preserve the basic Windows look. As much-maligned as the big Ribbon update for Office was several years back, at least it had the advantage of taking some functions that were buried under two or three layers of dialog boxes and putting them out in the open. Tell me, if you're not using a touchscreen, what the hell does Metro do for you?
Bottom line: change just for the sake of change is a terrible thing and should be kicked in the nuts.