I agree. Don't have the dock yet, but quickly realizing that it's going to be a necessity. Unless other like interfaces have come out since this post.
What I've learned in the past month since I bought an ipad.
Auria is hands down the best recording app you can buy, and completely worth the $40. Not much that you can't do with it, and it's pretty user friendly. IMO it's the only DAW for IPAD currently evailable that isn't just a toy.
As fer the interface, PLEASE PAY ATTENTION!!!! I went the inexpensive route and picked up a $50 Tascam iXZ. My thinking was that I'm half deaf anyhow, and the sound quality difference between an interface that plugs into the headphone jack vs one that goes into the other connector wouldn't be discernable. Wrong. Dead wrong. I have to get myself one of the others. Here's why...
While an earphone based interface might be fine for notepad type demos, if you want to do any real recording, it's uselss. All kinds of noise somehow leaks in, and while that might be just with the particular one I bought, they have other issues. If you try to use any kind of guitar amp modeling, well, ya pretty much can't. Anything overdriven screams with feedback like a mofo. And even if you do get a workable sound, the end result is horrible. I'm not talking stuff only an audiophile would notice, I'm talking bad.
Bottom line, if you're planning on doing anything other than just sketchbook type demos that only you're going to be listening to, I highly recommend getting yourself a good interface, and one that doesn't go through the headphone jack. And Auria.
Pretty much just a big +1 on hover's post, with a little bit to back it up.