I try to avoid paper books completely.
Room is a major consideration. My house in Greece is still full of books (though I've given away a full carful of them...). I divide my life between different countries and different houses, and have to move rather frequently. Carting loads of books around, especially with the speed I read, is a major problem.
Secondly, I'm spoiled by the extra options the readers offer. Suddenly I hate it when it's difficult to keep a thick paper book open, and I have more than once tried to double click a word to see its definition
Funny the things you take for granted for a lifetime, and then suddenly they start to annoy you...
But I still like going to bookstores and browsing. Only now, instead of leaving with tens of newly purchased books under my arms, I leave empty-handed. That feels strange.