Originally Posted by
Nelson_De_Souza:
“BIB I don't disagree with that statement as such, but to me that applies more to the companion than the Doctor. They are the ones we experience the show through and I've no issue with them changing as that's only natural, but with the Doctor it's not how I see the character. To me, he could and can be affected by things changing but it shouldn't be showing outwardly. If it does change, it should only be subtle ala Eccleston as you mention (that's the only good use of it for a Doctor since I've watched the show in my opinion)
Capaldi's change has been sudden and been jarring. I don't like the angry and rude guy he was at first and don't like what he's become as it doesn't suit and it too far detached from what he began as. That's poor character development in my opinion.
And I still disagree about the issue you have about Matt. The whole point was that his Doctor was awkward, that's why his speeches jar from poignant to the silly. His mind is all over the place calculating things and trying to frame it right in that instant. It was more prevalent in Matt's Doctor than anyone else's. That was his Doctor. He was silly then serious in a split second, that was the case from minute one of his era to the last. I don't see how he changed like you're claiming he did? 
And catchphrases were a part of that Doctor. A catchphrase doesn't mean caricature. That's there to keep things familiar and consistent and he wasn't using them every minute of every episode, they were used sparingly. I think you've over-egged that side of things if I'm honest.”
That does just boil down to the way we view the characters then. I'm of the opinion that you're somewhat limited in what you can do in terms of 'developing' the Doctor as a character. Companions will come and go, and can go on any journey the writer wishes. The Doctor has some fundamental constants that must be kept in place through and through. But you don't want a boring or predictable character at the centre of it all either, and so I think it's important you make sure he's able to develop in other ways over time.
I also think that Capaldi's change has been mostly subtle - apart from
The Magician's Apprentice which seemed to hit us around the head with it. His earlier hostility is still there by the end of Series 9 (the way he talks to Rigsy, the way he threatens the Timelords etc.), but equally his later vulnerabilities were all present earlier on as well (he admits in his first episode that it hurts that Clara was struggling to see he was still the same man, for example). His entire personality has been there since the start, it's just over time different aspects of it have come to the surface...arguably his more redeeming qualities have taken centre stage in time.
There's a difference between awkward Doctor, and frustratingly written Doctor though. There's some real touching scenes between the Doctor and Amy in Series 5 - his awkward chat with her about losing people in
The Pandorica Opens was brilliant, as was his heart to heart with her in
The Big Bang and
A Christmas Carol struck a brilliant, fun and often hilarious balance for his Doctor ("...got my name written all over it! Well it hasn't, but give me time...and a crayon!") in particular. But then Series 6 involved a story arc that put one of the fundamental unchangeables centre-stage - arguably the biggest one. We all knew the Doctor couldn't actually die, and so the Lake Silencio story revolved around the supposedly clever way they were going to get out of this one. The Doctor's dialogue reflected that supposedly clever writing ("haven't you figured that one out yet?"), the Doctor's own death mystery took canonical precedent over the regular episodes of the show ("or we could just have some adventures...") and then when the story arc fell flat so too did the Doctor's smug, catchphrase-ridden dialogue. He insists at the end of Series 6 he's gotten too noisy and must retreat into the shadows, then the start of the following episode sees him blowing up a spaceship over WW2 earth. There's so many aspects to the writing at this stage that were frustrating, and the catchphrases at that point were among them. Only my own personal opinion, and how I felt about the show at the time (frustrated...so much potential and so much of it wasted).