To the one question... this is somewhat like tofu. They both use the same methodology to display text. However, this is an e-book reader, tofu is not. Tofu handles only basic text documents and some pdfs.
This is a unique little application, but it is far from being complete:
1. It doesn't handle .chm or .pdb e-book formats (and might not handle others I couldn't get my hands on), it opens them without complaint, but all you get is ascii hash.
2. So far it only recognizes the very simplest of chapter headers and ends up crashing some other text together in odd ways, making it difficult to read and sometimes hard to differentiate parts and story flow. Either better auto-recognition should be used, or a set of options to recognize certain features.
3. It sometimes blows the formatting rather badly... though I don't know if this is due to misinterpretation of the text or the multi-column display process.
4. It's far from complete when formatting .pdf files. One file I opened it was missing large chunks of text and all but one image, and it couldn't handle almost all the formatting. This made it very difficult to read since numbers were appearing in the text that didn't belong, and pieces of text were out of the correct positions and not displayed correctly.
5. As far as X/HTML is concerned, it can't even handle the most basic formatting (italic, bold, links, etc.) and that's just the start.
6. The "Themes" function has major bugs, at the moment I cannot get it out of a black or dark background, and the set background color doesn't work at all.
One main test I do with all software is Unicode compatability... unfortunately I could not locate a Unicode formatted e-book to download, so I was unable to test this... so can it display kanji or arabic, or sideways text? I have no idea.
Though I would never use it, since there are too many hijacked crappy e-books out there already, this apparently also has an export feature, which might prove useful in book reviews where capturing quotes is necessary. However, since many of the listed formats cannot be read by the program at the moment, I question it's ability to actually export any of these accurately or at all.
Though this is a very good start for something that everybody has been screwing Mac owners over for the last several years, it has a long way to go. In it's current form, I wouldn't pay even $2 for it, let alone $15. I certainly wouldn't use it to read e-books until it handles almost all of the formatting problems (I can use 4 different programs that do this right, and are free, at least for most e-book formats). And most intelligent publishers use .pdf for manuals and textbooks, so the system handles that just fine with "Preview."
As far as stability, I didn't spend too much time testing it on that, but nothing I threw at it destabilized it in any way, and I did have quite a number of windows open at one point. Though I suspect, it's easy to make things crash-proof, if you make sure everything being input is converted to plain ASCII or preformatted .jpgs.