Even though the cheap upgrade period for Windows 8 is past, there are still many good reasons to consider Windows 8. Being a Windows 8 user myself, I do not really understand the gripes I have heard from other users. I've heard many, but I just don't see them. I will agree that Modern/Metro UI is different, but using it for awhile has made it second nature to me. Also, Start8 by Stardock Software is worthwhile checking out if you are unsure of Modern UI.
My chief reason for upgrading was a blown Solid State Drive. It was a good excuse, and lets be honest here, that should be reason number one to upgrade.
Note: This list is not a ranking of best to worst reasons.