They have messed with Trek canon just a bit, but this is explained by [minor spoiler alert] a time-traveling accident that means all of the movie's events happen in an alternate timeline. Very convenient when it comes to future movies, because they can basically do what they like.
There was a fair attempt to establish relationships and personalities, but I don't think it went far enough (particularly between the Big Three - Kirk, Spock & McCoy). Still, as an introduction it was fine.
But the funny-faced ewok? BAD.