I'm pretty skeptical when products claim to be good at generating website code, and when a product comes out like Artisteer than generates HTML templates, WordPress themes, Drupal themes AND Joomla templates all from the same interface, I was REALLY skeptical!
I bought Artisteer more out of curiosity than anything because I wanted to check out the code it generated. I was really quite impressed! The Extensoft people really did their homework on WordPress themes and especially creating code that works well in different browsers.
We use Artisteer to create our template packs that are free to download. One caveat though, Dreamweaver doesn't really play well with Artisteer templates, so if you plan on editing your templates visually after creating them, you might want to grab a different HTML editor like HTML Pad Pro.
But if you want a simple and fast way to create custom WordPress themes, check out Artisteer.