Initially, only the Web version is available. You can play it now at: http://beta.wazhack.com/play
Each new class has brought a new major feature or upgrade to existing features, all of which are relevant to all classes. So while the Bard starts with a Lute, any character could find one (though they are rare of course). The Rogue and Thief similarly use Stealth, which is now much more relevant to how monsters notice you, regardless of what class you are playing. I'll leave you to discover the value of the other classes yourself.
Talents now must be upgraded together more - no more just going straight to level 3 on a single talent. This is to keep balance while allowing talents to be significantly more powerful at levels 2 and 3.
In the Guild Hall you'll find the new Achievements list - a good way to keep track of your deepest journey or for veterans to find a harder challenge or two.
There are also a few more items, and a few new monsters and changes, far too numerous and spoiling to list here.
I'm only one person so there will be bugs. I'm still nursing a broken arm, but I'll try to fix them as fast as you can report them. The best way to report bugs is via the in-game menu option (it sends a copy of your game for me to analyze). If the problem is more abstract or gameplay related, by all means start a discussion here, or on the Reddit Forum.
Thanks for helping, I hope you enjoy playing the new classes as much as I enjoyed making them!
Have a Merry Christmas / Hanukkah / Kwanzaa / Odin's Day!