That would be my only real problem with the show (most of which I really enjoyed) - I just don't see Galadriel as the same character. Don't get me wrong, I
like this Galadriel well enough (and quite enjoy Morfydd Clark's performance) and I can absolutely watch and enjoy the show anyhow. BUT - I just don't see her as the same person at all.
I did think of one solution to this though - it's not her aging a few more thousand years - it's that she doesn't appear to have much in the way of psychic powers yet. I can see her personality changing quite drastically if something (like say, her ring) unlocks her psychic prowess. THEN she could easily develop the calm stillness she shows in LotR.
Anyone more hip to the lore than me (say,
@Maxperson ) know when/how she became a powerful psychic (she's downright clairvoyant, as well as telepathic, right?)
For a guy that used to be able to fluently write in Tolkien Dwarvish (like runes on the cover of the Hobbit) and Tolkien Goblin (from the Father Christmas Letters) and a tiny bit in Elven (just the letters, not the language) - I'm not much of a Tolkien buff, perhaps surprisingly. I've forgotten most of all of that, along with what I remember of any of the books.