Anderson started out as a great visual director, and while he gets the "kid in a candystore" syndrome that has killed the plotting of many of his films, his visual flair working on someone else's script elevates this film far past the wince-inducing bad previews. It doesn't hurt that the cast is top notch...all three Musketeers give great portrayals, d'Artagnan becomes charming after the 1st 3rd of his scenes, all the baddies are well-cast (although it appears poor Mads may have had physical problems during the end sequences that they were trying to cover), and even the incidentals, such as d'Artagnan's father, stand out in great performances. Jovovich shines in almost anything she does, and she's excellent here. Constance....we need to drown Constance. The one misstep in casting. It's like trying to watch Keanu Reeves in Shakespeare.
The script is where the problems occur. It's not that they took liberties...what they changed all logically makes sense in an alternate tech timeline and are really quite well done if you don't hate the fact that they changed things. It's certainly better than the Disney script. It's not that it's a badly structured script...it's not. No, the problem is that they don't know when it's good to be over the top, and when it's too much. For instance, the first act is fun, but too much, too fast (complete with comic booky Guy Ritchie style introductions)and too Mission Impossible: The Steampunk Years for the majority of the rest of the film. It makes the climax, which should be over the top for this film, a little anti-climatic.
But when this film works, it really shines. There are scenes in this film that just play like the scenes you'd remember from your favorite comic books as a kid, with punch and visual flair. There is an undeniable charm to this film that makes me want to own it on Blu and watch it every now again, despite what it does to the source material. (And there'd be a great drinking game trying to find all the nods to all the films made.) If you don't mind the deviation from Dumas, it's very much worth checking out.