It's pretty sad, I really liked the guy. It was pretty obvious from his show how passionate he was about what he did. He was the first guy that I saw who got so excited while describing seemingly normal animal behavior, he would explain things like a kid discovering magic for the first time.
My fondest memory was when he was talking about this croc, and it bit his hand and held it for like 10 seconds. He was totally cool the whole time, and when he finally got his hand free he continued presenting, with his hand dripping blood. If it was me I would have been crying for my mom and/or fainted.
p.s. Click the title of the post to read the BBC news report about his death.