I think that for the £25 the upgrade cost it was worth it.
I think the ribbon interface for explorer is fantastic, who hidden files and file extensions are now both right there on the ribbon rather than buried on the second tab of a screen opened from a menu.
The OS is noticeably faster than 7, dual screen support has been improved. My USB 3 ports work properly, they were temperamental at best under 7.
There are some nice cloud based features, my user profile settings for desktop colours and backgrounds are synchronised from my desktop to my laptop. My list of wifi networks and keys is copied between computers for me. My music collection is available streamed from the web without me ever having to do anything with my desktop where the music lives.
There are issues though, in 7 if I want to attach my printer I just click Add a printer and windows does everything else. On windows 8, it find the printer but I have to use an advanced add screen and refresh my driver list from Windows update before it will install. The start screen is annoying, it's not useless just there's no point to it. In most ways it's a backwards step from the previous start screen.