First things first: Klingon ridges? I don't think there are any words to describe my opinion on what they did to the Klingons' heads...
Second: didn't anyone else find Khan a bit weepy?
Thirdly: the characters were not themselves as they were in TOS. Granted, this is an alternate timeline and everyone is a lot younger, so they may yet grow into these more mature characters. The franchise 'has' to be updated to be a box office hit, but I think it lost something in that.
On Kirk attacking Khan on the Klingon planet, again alternate timeline, but the original Kirk would not have done this I think. In one episode of TOS, Spock asked Kirk if he really wanted to kill [that person], to which Kirk replied "Yes I did. But man has learned to surpass his instinct", even when he thought a close member of his crew dead.
If I were a critic (albeit biased towards Trek), I would give it one of the highest ratings I have ever given a film.
One of my favourite lines from the film: "Can you stop with the damn metaphors, Bones!"
And on why Khan was white and not Mexican (yes, and Indian character played by Ricardo Montalban), a lot of British ex-pats live in India, and over time, have acquired or been given Indian names through marriage or birth. Just like it's not uncommon to find a thoroughly Indian man named George Smith.