Windows HATE (8)

I bought a new desk top at the weekend that was loaded with Windows 8.1....is it me or is this the worst OS ever, So far it has proved to be much slower than XP Prof and I am constantly bombarded with adverts and pop ups, Is there a way to get rid of all this crap, I only updated??? because I could no longer connect with Garmin for the map updates and our smartphones would not integrate with XP.....so far a resounding FAIL.

Can anyone with more tech savvy/experience of 8 give me a nudge in the right direction.
Cheers
Phil