I really wanted to love this but as it stands I merely liked it okay. I'm surprised to hear all of you praising the action because frankly I thought that to be one of the weakest links. This is a recent problem for both Spielberg (clearest in Skull but evidenced in some of his weaker efforts like Lost World also) and Jackson (King Kong but a little in the later Rings films) of overcrafting their set pieces. They push them way too far over the top to the point of absurdity. It's no longer thrilling because it's just impossible and ridiculous. In Skull you had that idiotic crystal skull juggling act in the jungle which Spielberg repeated here with the scrolls. In Kong there was the dinosaur falling through the vines. The freedom of CGI has absolutely destroyed these filmmakers ability to tell the difference between what is exciting and what is stupid. When a set piece merely clicks into place like a piece of clockwork something has gone wrong in it's construction.
I don't think Tintin needed any backstory, but I could have done with a few more quiet moments between him and Haddock or Snowy or whoever. The most fun comes early in the film when Haddock and Tintin are verbally sparring, getting the keys to the alcohol, etc. Also not enough weight is given to death... oh the guy died on my doorstep and left a message in blood, no biggy.
All of that said Spielberg is still a top class visual storyteller. I simply admire his ability to move from shot to shot. There's almost always a visual cue which allows him to properly cut away. For instance when Tin Tin is looking for his magnifying glass the camera follows him around the room and then Tin Tin moves away and we cut between all the framed stories on his walls... then back to him and to Snowy with the magnifying glass, etc. There's a fluidity to the visual progression here that very few filmmakers can match.