Well, this is a rather timely thread for me. This weekend I installed and started using DAW Remote HD on a 1st generation iPad. So far, so good.
Easy install and setup; on both the iPad side and the Mac/Logic 9 end of things.
Very good responsiveness (not perfect, but much better than I expected).
Jog wheel can be toggled between Jog and scrub, is very responsive in both modes.
Transport section works very nicely.
I'm using it primarily to control Logic from a synth that is too far from the Mac when I'm working solo in the studio. Works great in that context, I never have to look at the Mac's monitor, all the info I need is on the iPad's display, along with all of the controls I need.
I like it enough already, that I've started using it as a control service when I'm right in front of the Mac. We'll see how I feel about it after a full week of working with it.
One thing we do that may help the responsiveness is that we have two routers available to the studio. One has Internet access and is used for general Wi-Fi/Internet activity. The second router is an Apple Time Capsule with no Internet access that we network only the actual studio devices via (used for active project backups, to exchange files between the Macs and to connect iPads to use apps like Spectrasonics Omni TR and DAW Remote HD).