I'm an old (but relatively casual) RPG'r that started with the orignal red box, AD&D, Ultima series on C64, etc. Baldur's Gate in the late 90s rekindled it for me, and the pending release of the iPad version is actually how I found Avernum.
I've read Jeff's blog posts (linked through HN and Gamasutra), but sadly never checked out the games. I stumbled onto Avernum while searching for more info on BG iPad. Decided to buy it and check it out, and wow! It's what I've been missing. I just can't get into AAA FPS RPGs that feel more like a Michael Bay flick than an RPG experience. (ok, Fallout 3 was a rare exception, but still didn't feel like an RPG to me).
I can't compare the iPad version to the desktop, but I do feel that 'touch-and-click' is simply more intuitive than 'point-and-click'. Keyboard shortcuts would be an awesome time saver, but I can live without them for the portability, battery life, and pretty IPS screen. I don't understand the criticisms (on App Store) that the characters are too small, but I guess I'm coming from a traditional perspective rather than a Pocket RPG perspective. I love, love love this game. I hope only BG iPad (given the budget...) can keep up!