I clearly had NO idea that here inPhoenix I would find ANY Thai restaurants that are remotely authentic that might rival the best of those in LA or the Bay Area and most especially Thailand. Well, having lived most of y life in San Francisco AND lived in Bangkok for a while, I can say this is easily without doubt, as good as you can expect it to get for Thai in Phoenix.
Chanpen is the real deal, and while not the best Thai restaurant I have been to in my life, it is absolutely fantastic and offers the a genuine, authentic Thai experience for those who know their way around the block and know how to order authentic Thai.
Try the Kapow Gai and ask if they have Chinese broccoli ( hit and miss). It's great to add some veggies! And the Tom Yum is excellent and another MUST HAVE dish would be the Larb Gai, but be sure to ask they make it Thai style - with cabbage and NOT lettuce (YUK)! That's how the dish is intended to be eaten.
Nothing fancy here at all, and the place is small and unpretentious. But service is good and staff friendly. Come with friends and eat Thai style - family style and you won;t be dissapointed.