It's not as bad as the opinions of those above make it seem.
But regardless of whether it's good or bad, if you already have 7 then it makes little sense to upgrade at this time unless you really want to. The changes arent really that astounding (if I never used the start menu i'd probably forget I'd switched). Unless there is a program you need 8 specifically for (which I am not aware of any) then there really isnt too much of a point for an upgrade.
My advice is generally:
If you are buying a brand new OS to install (like for home-built computer) or are upgrading from something older than 7, then go with Windows 8.
If you already have 7, then stick with it, upgrading is a bit of a waste of funds and you don't really gain anything...