This is a very ordinary version of The Three Musketeers. Film versions of classic novels should at least bear some resemblance to the plot of the novel from which they are adapted, even if they are just pot-boilers intended for a family audience like this one, and not meant to be taken too seriously. But this is a very loose adaptation indeed.
The acting is just up to the level required and the dialogue is a mix of pseudo-17th century and contemporary Americanisms which fail to convince the viewer that he/she is watching a picture set in 17th century France. Though the production is quite a handsome one, with the sets, locations, and costumes all nice to look at, the characters are not well-drawn, in particular those of Cardinal Richlieu, portrayed as an out and out villain, admittedly enjoyably, but with little depth, and D'Artagnan who is played as naive, arrogant and pompous and not as a particularly likable character.
Other comments stress that this is a Disney picture made for the family, but that should not save it from criticism. Compare it with Disney's Treasure Island, or Kidnapped, both much superior adaptations. Nor have they helped children understand the novel. Because it is so loosely based they would hardly recognise it as The Three Musketeers if the characters' names had been changed, though I do agree that film adaptations don't have to follow the source novel absolutely faithfully.
But is it entertaining? Yes and no. The villains are hiss-able, Aramis, Arthos and Porthos are sometimes entertaining, despite the questionable dialogue they are given, and Richlieu, though often over the top, has his moments. The action scenes are OK but not done with any great verve compared with the Richard Lester version. Milady does not feature as a really central character in the plot as she should and in fact many of the novels' characters do not appear in the film at all.
Read the book and see the 1973 version and forget this one if you are over 16.