I loved Horizons and can't stand the fact that it was replaced with a ride that spins and makes people ill. At least make an attraction that is 'thrilling' but not so thrilling that you have to hug a toilet bowl when finished with it.
Makes me sad when I see the Mission Space building. And, even though I really enjoy Test Track, I miss World of Motion as well. I don't know, just call me an old softy, but I like those family type rides. Don't get me wrong, I'll freefall on ToT or twist and turn on the RnRC, but it's just not the same experience without my beautifully themed attractions like those two being included in my overall 'experience' at Disney.
EDITED: After checking out the "HORIZONS tragedy" webpage, I decided to check out my DVD on the Horizons history to reminisce a bit. Boy do I miss that attraction.