Happily, this app no longer crashes immediately on my iPhone 3GS, as of update 1.0.1. That said, I'd still like some changes in this before I'd be likely to use it regularly. Here are some thoughts on 1.0.1:
First off, it's a very cool concept. I've been interested in slit-scan photography for a while, and having a way to at least approximate it on the iPhone is a very welcome thing.
Next, I find the behavior of this app a little strange in a few ways: it is continually scanning (and, depending on your mode, re-scanning) the range of the sensor (or a single line of it), and (if set to save to camera roll) it saves roughly every 2 and a half full scans (worth), giving you a very tall (or wide, but the UI is always vertical) image, maybe 3:1 aspect ratio (I haven't measured... But the example outputs all appear to be two saved images placed side by side, with that placement done by something other than this app). This is kind of neat to be able to do, but I'd also like to be able to have it do a single scan and then stop, saving the image at that point, and not starting again until I said to.
I think that's my biggest request, though. It's definitely interesting, and I expect to play more with it over time. I only wish I had a good way to mount my iPhone on a tripod... Perhaps I'll look for something that will let me do that.
Keep up the good work! This app definitely has promise.