I finally managed to do some poking around on the PTR today after two days of trying to get my characters transfered over, and so far it's been a pleasant surprise. My alliance shaman hasn't made it over yet, but my horde paladin, shaman and warrior all did, and so I spent some time exploring the new quest content in Dustwallow Marsh. The Shady Rest Inn quest chain is finally completed!
So far, any fears that there aren't quests for the Horde in the marsh are overstated. I've found plenty on my Belfadin, between quests to blow up oozes with electricity, quests to wrangle raptor feathers, escort smelly people on flowerpicking expeditions, and kill Grimtotem Tribe who are acting suspiciously. There are suspicious hijinks afoot, let me tell you. (I'm trying to avoid spoilers here.) The quest drops are about dead-on for the level, decent greens that seem to plug up some itemization holes (including a nice mail chestplate, featured in the screenshot, that a newly 40 enhancement shaman would like as well as a nifty pally sword for up and coming paladin tanks) and while they're not crazy or overpowered, they're about just right for their level all told. Starter greens, yes, but solid ones.
Hopefully I'll get my alliance on soon, I want to follow up the Missing Diplomat quest chain. (Note, don't follow that link if you don't want to be spoiled.) So far, Dustwallow seems to be shaping up nicely for those of us looking for new mid level content.
Update: As my draenei has just popped into existence on the PTR, I have an awesome change to report: the boat from Menethil to Theramore now has a crew, complete with a vendor who even sells reagents. This, my friends, is really awesome.