This is really awful. I think this goes down as one of the most devastating deaths of the last decade. Leonard Nimoy really hit me harder than anyone, but Robin Williams and Carrie Fisher (with Debbie Reynolds to pack on the punch) were devastating as well.
I don't think anyone has ever battled ALS as successfully as him. He was diagnosed with two years to live in 1963. It's incredible to think of the amount of research and progress he accomplished despite his paralysis--only able to speak with an article voice controlled by a single cheek muscle.