Useful, but still use my MBA
I bought the original Ipad on launch day and still have it. Also have another original Ipad 3G that I ordered on launch day for it. The latter is the one I use most, almost daily, with the other one as backup, for reading books, etc. I still need my MBA and use it daily. I create lots of presentations, work up complex projects with Tinderbox, and work with spreadsheets quite a bit. I can't do these things on the Ipad.
I do use the Ipad a lot though: reading email, PDFs, jotting down quick notes, and surfing the net. I have unlimited data on AT&T. When will I buy a newer one? Maybe when they have a computer like file system access. That would be a big help.
While I am wedded to my MBA, I have often traveled with only the Ipad on trips where I did not have to do work requiring the computer. It is very easy to lug the Ipad, but the 11" computer is not that much bigger and does so much more.