I'm going to be playing a Genasi Barbarian in the campaign that's starting up this weekend, hoping it goes long enough for us to hit paragon where I plan on taking Elemental Tempest. If all things go according to plan...when he crits, he's going to crit HARD.
If one of the characters in the SoW game I'm running dies, I'll let the players try Artificier or Barbarian. As long as they're clear that it's a playtest and the character may need drastic changes if it's not working, or working too well.
Edit: Actually, I should really make sure it's OK with all the players first. Some of them may not want playtest material, and it's their game as much as mine.
That said, anyone interested in how the class is changing should go over to the Dragon/Dungeon Article discussion thread over on the WotC board and check out Logan Bonner's comments