I recently tried to introduce my son to them, but he just couldn't get into the series as it wasn't fast paced enough for him in the beginning.

Out of curiosity, and because of my praise for the series, my dad decided to give it a try...

I've never in my life seen him read anything for pleasure.

He's now >5000 pages in, just finished Fool's Fate, and is about to start The Rain Wild Chronicles (10th book in the series).