Even if it is a rip off of Kahn, at least they ripped off the best of the series.
I think a lot of sour grapes is coming from the hardcore fans. Now that Paramount is running things and Abrhams has the reins, it's more action orientated. Let's face it, The Next Generation kind of had a space hippy vibe.
Add to that I've heard this film features Section 31 and can see why old school trekkies are peeved. Section 31 was introduced in DS9 and was controversial in the Trek world. The Roddenberry crowd view Starfleet as a utopia, doing everything the right way. Section 31 was darker, a covert CIA type division in Starfleet, not above doing things others would look down on ethically.
Of course stuff like that is what made DS9 cool. It wasn't a goody two shoes Star Trek.