Did GoT ruin the image of the characters in your minds?

[Lonin]

Ruined - not many, some improved. I watched a couple episodes of season 1 before reading the books.

Dany - Emilia Clarke is clearly much older than book Dany, this was a good thing for me

Jorah - Iain Glen is both older and better looking than book Jorah, slowed down my recognition of some book Dany/Jorah dynamics

Sandor - Rory is older than book Sandor, slowed down my recognition of some book Sansa/Sandor dynamics.

Jon Snow - for some reason I just don't like the actor Kit Harrington - kind of ruined Jon Snow for me, Jon is the kind of book character that I normally like.

[Ser Aeron Appleton]

I'm of the opinion that the fantasy genre suffers from a severe lack of non-English language and culture, which tragically leaves the hundreds of other cultures that have existed during the Medieval Period alone underrepresented or misrepresented, not to mention those that have existed before and after. An American-esque Medieval kingdom would be wonderful, but to my knowledge no one has ever seriously bothered to conceive one. Worse, English/Scottish/etc. accents are used far too often to create the illusion of fantastical settings or "foreignness" without actually creating anything fantastical, or realistically depicting a foreign culture. That's why Star Wars stuffs random British men in between all the blue elephants and butt-faced creatures, and the ancient Greeks are collectively played by Gerard Butler. It might sound normal to someone who is actually from the British isles, but over here it's an attempt to capitalize on the general ignorance of the masses.

GRRM being an American writer of fantasy seems like the perfect opportunity to inject a little bit of my culture into the setting without compromising the overall vision. It helps me relate to the story better in a way, but it also makes the world of Westeros more interesting than the garden variety fantasy worlds of drunken Scottish dwarves, Irish hobbits, and Hugh Grant elves.

This is interesting and, dare I say it, cool. I'm retroactively adding this to my list of reasons why Varys should speak like Tennessee Williams.

But there are several different "British" accents. Not just English, Scottish, Welsh and Irish. I agree that there is an abundant lack of varied accents in modern fantasy including the many accents of North, Central and South America. However, I just find it hard to imagine Westerosi saying things like "Would that I could", "If it please Your Grace" or "I'll break my fast with you on the morrow" in anything other than an upper class English accent. Probably just me, sorry. I find it annoying in the show as well that the Stark family all have different accents i.e. Jon, Ned and Robb all sound northern english whereas Cat, Sansa, Arya, Bran and Rickon sound like their from down south. Inconsistent much. anyway, sorry for harping on at you ;D I guess in the end it's just comes down to opinion. I mean in my head when I read ASOIAF all the characters sound like me anyway because I'm reading in my voice.

[Wmarshal]

I watched show before book, and to be straight with you the book is so different then show that as I read on the way I imagined people changed. Save for Davos.