I've always felt sorry for Colin, after watching the end of a "making of " Documentary for "The Trial of a Timelord" he slightly blames himself for the dip in the show's popularity at the time. It wasn't his fault at all, the reason's his time on DW suffered was because of Poor Storylines and Poor Production, but it wasn't always bad his Season's had some Brilliant Episodes, such as "Vengeance on Varos", "The Two Doctors" and "Revelation of the Daleks".
The Sixth Doctor (in my view) was a Brilliant sign of things to come for the show and the character of The Doctor, he's Dark and at times slightly sinister (just like the Seventh Doctor), he's an all-action Doctor who doesn't need a Sonic Screwdriver to get him out of every situation (just like the Eighth), underneath his loud exterior there is a fragile more Human side to him (just like the Ninth) and he's Brash and Outgoing and certainly not an Introvert (just like the Tenth).
Colin was the first man to take the part in a completely new Direction, and if you watch his debut story "The Twin Dilemma" he gives us probably the most Interesting Portrayal of The Doctor ever, and that continued throughout his time on the show. It's a pity that we never saw more of the Sixth Doctor because if he would have been given the same stories that Sylvester McCoy had in has last 2 Season's and also if he had a say in what he wore for the show

I would love to read your thoughts and memories on The Sixth Doctor and maybe we can get some more Appreciation Topics on all of The Doctors.