Oh, Luis, you're funny

Having said that, all the rest is terribad. I'll start with the easiest bit. No, this star trek has not a better plot than Khan, I dare you to summarize the plot in a representative fashion, without convoluting yourself up. You can't.
On the contrary. After the movie was over, I was telling my wife about "Wrath of Khan" and managed to summarize that movie and the motivations of its characters in about 3 sentences. No way I could manage that with Into Darkness.
The plot is basically a set-piece after set-piece with emotional and adrenaline connections between them (I can't get out of my head the innumerous "runs" characters do just to make ST "not a bore", Scotty is the worst offender here), without any hint of a overall thematic more sophisticated than "Hey zis is boom boom ships laz00rs and KHAAAN" joyride. I have the temerity to think that movies should aspire more than being a rollercoaster filled with one-liners and emotional quickies. This is the movie equivalent to the current "soundbyte" and marketing politics, the equivalent of current autotune's musical industry.
Really? You don't think there's a connecting theme to this movie? I think you need to watch it again. Like NGTM-1R said, you apparently missed the majority of the content.
There is no character arc anywhere. There is no logic in Khan's actions, nor motive. There is no sense in general Marcus' actions anywhere, Spock is now an angst teenager who conceals emotions and Uhura gets mad at him for not wanting to jeopardize an entire ship for it. Kronos is a wasteland. There is *no story at all*.
Bull****. Kirk and Spock both go through character arcs, Marcus' actions are spelled out for you from the moment you first meet the man, and Khan's motives are also laid out for you, although his ultimate goals and background remain a mystery to the audience (an acceptable mystery at that). There is quite a bit of story packed into this movie amidst the action.
Star Trek II at least *had* a story. And it was a good story with good concepts all interwoven and linked together. The concept of a "no-win scenario", the growing up of middle-aged Kirk into the acceptance that there *are* "no-win scenarios", through the sacrifice of a friend. The death of a world and its rebirth, paralleling the death of Spock and the appearance of a son. The Moby-Dick-like obsession of a deranged intelligent man against Kirk. And it all fits together.
Star Trek II is among the most over-rated movies ever made. Allow me to summarize the plot for you:
1. Genetically-advanced madman wants revenge on Kirk for actions which occurred ENTIRELY off-screen during the original series.
2. Said madman takes over Federation starship.
3. Kirk, full of bravado, walks straight into a trap and learns some humility.
4. Technobabble hand-waving about Genesis device goes here.
5. Kirk learns his lesson when his friend Spock dies...
6. ...oh wait, Spock didn't really die anyway.
Wrath of Khan's plot really wasn't that good. It gets a lot of nostalgia and rose-coloured glasses treatment by Trek fans, but on its own its a medicore movie at best filled with a lot of technobabble, a lot of egotistical focus on Kirk that is ultimately wasted, and a lot of boredom in between. It is by far the best of the ST movies made before Abrams' reboot, but that isn't saying much... in general, the ST films have been poor substitutes for what made the actual series' so great.
The reversal of Spock and Kirk's last scene is the ultimate sign of how the movies have grown so much in flair and degenerated so much in courage and content. If they were genuinely interested in making the reversal, then yes, you should have Kirk killed in the movie. But at no moment I was really "afraid" of having this character killed. "Yeah, they're gonna revive them..." and so they did. ST II's final sacrificial moment was a amazing moment and this one is just sad in how empty it is. It's like decaffeinated coffee all over the movie, disguised with lots of CGI, camera-shake and Scotty's runs.
That reversal was perhaps the best moment in any remake film I've seen, not just Trek. It did so many things - it pulled in Trek fans who've seen Wrath of Khan because the dialogue was entirely replicated; it connected these alternate universes in an interesting way that shows, despite history being entirely altered, there are some events that are so important that they will still occur, albeit with slight differences; it allowed both Kirk and Spock's characters to finish their developmental arc (Spock's character did not experience a change in Wrath of Khan).
While I agree that the tension could have been heightened - the foreshadowing concerning Khan's regenerative abilities would have been sufficient from the beginning without the resurrected Tribble - it also could have been seen as a deux ex machina device had it just been pulled out at the end again. Killing Kirk entirely really wasn't an option.
STID missed some opportunities in a few places - I thought those 72 torpedoes were going to turn out to be Genesis devices like in the original movies, which could have made Khan's actions on Earth redemptive by preventing the annihilation of the Klingon homeworld - in general I still stand by my previous assertion that the Abrams' movies are actually the best of the Trek movies yet made (mostly because all the others are genuinely medicore to bad films that are not accessible to newcomers).
In general, I think Axem's page 2 assessment is bang-on.