He's a pretty great person from what I can tell, very witty and funny in person too (I saw him very briefly at a book signing before I knew who he was) and people like that deserve nice long lives.
I enjoyed Nation as well, but it didn't appeal to me as much as the later Discworld novels. Pratchett has started to deviate from the older characters' stories a bit, but still has some of them help the story along a bit. I quite liked Unseen Academicals and Monstrous Regiment because there were very few previously used characters appearing in them, but I still have a fondness for the older story arcs.
I might. I think I was just burnt out on Discworld and the same characters popping up. I remember now that I read Nation not long ago and really enjoyed it.