Go HORACE Go !!!
After reading this article I tried hard to think back to my speccy+ when I was about twelve (oh how I loved my speccy!) but I cant remember the Microdrive.
After reading the comments I wondered if anyone remembers the little cartridge type things that plugged into the slot on top of the interface. I think they were called Rom Packs and I only ever had one which was a game called Jet Pac (developed by Ultimate/Rare I think). It only took about one or two seconds to load and I loved it. No having to wait 5 mins while a tape loads only to end with a ' R tape loading error'.
No matter how hard I tried though I could never manage to find any more 'Rom Packs' in the shops and although I don't remember how much they cost, I wonder how things would of turned out if Sinclair had pushed that side of technology more than tape or Microdrive?