The Historian at MythVillage pointed out two new Myth III reviews.

GamesDomain not only liked the game a lot-- in fact, they liked it better than the previous two:

This is the best game of the series, which is saying a lot considering the accolades lavished on its forebears. The upgraded graphics help, but the real treat is how the story weaves into the gameplay. Crossing a bridge into a horde of monstrous Trows takes on a new meaning because you might lose one of your favorite heroes, someone who might be integral to saving Gower and its inhabitants. Few strategy games offer this kind of character interaction.

GameSpy was a lot less enthusiastic, detailing many of the technical problems: lack of Windows 95 or XP support, requirement of installing QuickTime (that's a bug?), problems with various video cards, etc. They also didn't like what they didn't find:

Then there is the case of false advertising. Right there smack dab on the box it says, Create your own units or even entire worlds with the easy to use editors. Ignore this. It's a fib. The game doesn't come with an editor. Mumbo Jumbo has since stated that the editor (dubbed Vengeance) will be available as a free download soon, which is all well and good, but if a feature made it onto the box it should be part of the package. And an editor is sorely needed because the game ships with five, yes five, playable multiplayer maps.

They conclude by rating the game 75 overall, and saying that it's got real potential if the coming patch fixes a lot of the problems.