I've played a little bit on the ptr with my then lvl 21 pally from live complete with heirlooms and have to say the new bosses in both deadmines and stockades are a lot more fun then the previous bosses. I love that they have beefed up all 15-60 bosses health (and damage?) now boss fights will feel like boss fight instead of them dying in 10 seconds :P
how will new players fair in the beefed up instances? Hogger in stocks has 10 times the hp as bazil used to!