i think the first dumbledore seemed to grandfatherly because he was a but more grandfatherly in the first two books. His character wasn't super developed. He was just this funny old guy who knew everything about everything. Kinda like a grandfather.
Agreed, michael gambon is not right for dumbledore. He's too aggressive. The beauty in dumbledore is that he doesn't rise to anger (except in dealing with voldemort, and even then!) He's calm and collected and wise. This dumbledore comes off as rash, angry and impulsive. There is no tricksiness about him. Also, his looks. He looks grubby. He has dirty fingernails and a dirty beard. Dumbledore is suppose to be so magnificent looking. Sparkling blue eyes, long white white beard. Sweeping beautiful robes.
I think the ultimate dumbledore (to replace richard harris, whom i think would have been better in the alter films) would be patrick stewart. Think about it. Hes great in a role of leadership (jean luc picard!!! CHARLES XAVIER!!!). He can do trisky, he can do calm and soft spoken. When dumbldore get's superb bad ass, ohmigod... if it was patrick stewart, it would result in multiple orgasms. All he needs is some good makeup to age him. Can you imagine him blasting tom riddle a new one? HOT!
ohhh patrick stewart. he's a god amongst men.
