I don't normally post in "R.I.P" forum threads, but this is a real sickener.
I remember thinking "that doesn't look too good" when his illness returned after being in remission... even so, and much as I loved the series, I'd hoped they'd put it completely on ice unless/until he could return. After a dodgy start, he grew into the role and in the end absolutely owned it... hard to imagine someone else in the part, although the show will go on I suppose.
From what I saw on interviews, he came across as a genuinely nice guy who was a bit bemused by it all, not the slightest hint of conceit or luvviness (he was an engineer prior to his acting career I believe).
**** this wretched disease.