I saw number of threads here where people asking advice on how to get rid of ugly popcorn ceilings. One of the options you have is to cover it with Polystyrene ceiling tiles
. The best thing is - you don't have to scrape the popcorn - those tiles installed straight on top of popcorn, so your job will be much faster and cleaner (actually there will be no mess at all).
Basically all you have to do is to draw straight line and lay the tiles one by one covering the popcorn once and for all.