Okay, I'm just going to get this fact about me out of the way, I'm not a Whovian.
I grew up in a Whovian household, but I never could call myself a Whovian. My dad and my brother love this show, but there was something about it that didn't exactly appeal to me. Perhaps it was the characters saying too much scientific mumbo jumbo for my taste; or maybe the effects are too lame; or maybe there's something about having the main character die and come back as someone else that doesn't really strike a chord with me; or maybe this whole fandom seems very overblown, and thus, makes the show a tad overrated. Whatever the reason, I don't consider myself a huge Doctor Who fan.
When you became the Doctor, I started to appreciate the show a little more. Sure, there was much of the same scientific talk to explain---or at least try---how to defeat the bad guys, but I was able to overlook it somehow.
For one thing, you seemed closer to the Doctor's previous incarnations than Smith and even Tennant did when they were the Doctor.
Now, I realize there are a lot of Whovians who love both of these Doctors, but I can't call either of them my favorite. David Tennant was eccentric, charismatic, and good-looking, but he was hiding his Scottish accent, which indicates he's scared of being his true self. And as for Matt Smith's Doctor, don't even get me started!
But I really loved your Doctor. Maybe it's because of your age, but watching your episodes, I really felt like I was watching the Doctor fighting monsters and saving planets and not some young British boy running around being the hero while also posing for a cover of a GQ magazine.
Your character is everything the Doctor should be: patient, kind, and generous while also being charismatic, eccentric, and selfless. Not cruel, cowardly, or too ruthless. And you're not afraid to let your Scottish accent shine through. And to add to that, not only do you look classy wearing sun shades, but you also play the electric guitar.
How can you argue with that? You didn't have to say, "What I am doing is cool" or "What I'm wearing is cool." (On a side note, even if bow ties are cool---which they aren't; I'm sorry, but they really aren't---you shouldn't have to announce it.) Your Doctor is the definition of awesome.
But alas, as with all the Doctor's reincarnations, you can't go on forever. Earlier this year, you made an announcement on BBC Radio, that the show's tenth season will be your last one as the Doctor.
While regenerating Doctors is nothing new, it doesn't make the news hurt any less. Not only do I like your Doctor a lot, but you are my favorite Doctor. I've gotten to know you, and I appreciate you. And when that day comes when you have to regenerate, it's going to be a sad one indeed. I don't want you to go.
But, I found a silver lining. Since I don't call myself a Whovian, I can say I like you in other things. It worked pretty well when Tennant left the show---he excels in Shakespeare, and I love him in Broadchurch. If I can say I like seeing you in your next project that may or may not be related to Doctor Who, then maybe watching your regeneration scene won't hurt as much.
And what's more, I don't even have to pretend that's true. You were a killer Cardinal Richelieu in the Musketeers. You rocked it as George Harrison (my favorite Beatle) in John and Yoko: a Love Story. And of course, who could forget your hilariously brilliant performance as the f-bomb-dropping Malcolm Tucker on the Thick of It?
And you also established yourself as a great filmmaker. (On a side note, Franz Kafka's It's a Wonderful Life, which he won an Academy Award for, by the way, is a short film that I would recommend to anyone who's ever been curious about Capaldi's talent (or maybe even about Franz Kafka)). And there are a couple of other films you had a hand in either writing or directing that won critical acclaim.
Whatever the performing world has in store for you, I wish you the very best. While I'm going to miss you as the Doctor, I'm excited for the next time I see you on the small or big screen. I know you're going to be awesome because that's what you are. Rock on, dude!