I'm rather puzzled by all the criticism of ZQ.
First of all, Spock has been my favorite character from the time I started watching TOS in 1966 through today. I adore Nimoy and think he did a wonderful job creating Spock, and by extension, much of what we think of as "Vulcan". He is an unusual looking man, tall and thin, with interesting planes to his face, deep, narrow eyes, a deep sonorous voice and a specific physicality that have all become inseparable from the character for many fans.
I think I fell in love with Quinto's Spock in his first scene, when he takes his mother's hands, and stares deep into her eyes with concern. And the f**k you to the Vulcan Academy elders was a stitch.
I thought ZQ really became "Spock" on the Enterprise - that scene where the "pointy-eared bastard" enters the turbo-lift, cocks his head, and then strides across the bridge to the science station - the body language was so "Spock", I was totally hooked at that point. I also thought Zach nailed the confrontation with McCoy (classic TOS), the fight with Kirk, volunteering to go onto the Narada - OMG his expression when Kirk claps him on the arm is priceless Spock. And as everyone has already noted, the moment where he sits down in the Jellyfish and intones "fascinating' could be Zach channeling Nimoy.
Most importantly, Zach as Spock has a lot going on behind the eyes onscreen, you can sense an active inner life, even when he's not the center of the scene or has many lines. You have to have an actor for Spock who can show a lot with a little since the character is requireed to keep everything bottled inside. Zach is an expressive physical actor, just little body movements, tiny changes of facial expression and voice inflection convey so much. Nimoy did this very well and so does Zach.
It simply isn't possible to duplicate Nimoy, and it would be disastrous IMO for an actor to mimic him. NuSpock is a younger man and his life path will be a different one. But what we do have is the essence of the original character, and an actor who made the role his own, who resembles the original actor as closely as was reasonably possible.
Of course, if there's one thing I've learned on internet forums, it's that fans aren't necessarily reasonable by any reasonable paramters of the term.