The truth is: there are 100's of different impressions on what is "true to canon." However, I'm inclined to believe that if you are one of the people who analyzes every frame of Trek, analyzes every syllable of dialogue, you will probably be alienated from this film.
But there's a vast difference in being loyal to canon and being a slave to insignifcant details. I think the vast majority of people take canon to mean the story elements that make up Star Trek and the characters we have loved for so long---not the button sequence that was used to open Kirk's "safe" in his quarters or how the Bridge of the Enterprise is designed or even what the uniforms look like.
This film can absolutely tell a brand new story with a brand new look and new actors and still
be 100% loyal to established events in Star Trek. I suspect that's exactly what will happen, too.