First off, just to be totally clear, this app generates a plain text file (and not an image file). Text which I could perform further manipulations on is exactly what I wanted. Great!
The app gets bonus points for working with layered PSD files. No need to flatten, easy to make subtle tweaks in Photoshop and roundtrip back to Photo2Text — just in case you can't figure out how to adjust the image brightness, contrast, etc. within the app itself. (I didn't figure out how to trigger the built-in editor controls until I started writing this review: there's no button for it. Once you're in the editor, you need to double click the image again.)
Photo2Text had no trouble generating text mosaics with 1000 characters per line. It may be able to go much higher than that, but I didn't check. 200 characters per line ended working for the poster I was making.
Lack of basic written documentation and the aforementioned lack of an (obvious) button to trigger the image editor controls are this app's only defects.
My one feature request: I'd love it if there was a way to tell the app to use specific, limited character sets in its mosaics.
If you remember the Panopticum Digitalizer plugin for Photoshop 6 — and if, like me, you've been waiting for a replacement for years — Photo2Text will do the trick.
Did I get my $2 worth from this purchase? YES! And here's the event poster to prove it: http://sf.nerdnite.com/2011/10/14/nerd-nite-sf-17-open-source-toxoplasma-and-b-horror-science/