As a kid, I didn't quite get Troughton. As I got older, I liked his Doctor much more. I realized the genius behind the persona of the Cosmic Hobo, that Bill had been the Grandfather (literally), very much the gentleman but curmudgeonly and stubborn at times. Troughton was more child-like, more in awe, but he also used that facade to dupe many an enemy.
He was also a brilliant actor outside of DOCTOR WHO. I still love seeing him as the priest in THE OMEN, even though his part is rather short. I think it's sad that he wasn't able - or, perhaps, willing - to give up his vices even as they were killing him. Having one lung removed due to cancer, but continuing his habit which eventually took his life is a tragedy (I'm not judging, I'm currently trying to quit smoking again, so I understand the addiction, and I know full well from his example how my own life could end).