So I finished reading my first book on iPhone's Stanza app (see original post on it here) and I'm definitely pleased with the experience.
The typeface was easy to read (much easier than reading email or web pages on the iPhone,) the application automatically took me back to the last page I was at, and there was no need to keep the lamp on if I wanted to read at night (an occasional bone of contention in our house) and I didn't miss the feel of the actual book anywhere close to what I'd anticipated.
It's definitely a habit I'll keep up, especially if Stanza keeps getting more and better titles.
UPDATE: Even cooler: Someone from Stanza got in touch with me on Twitter to thank me for the post and to ask for any suggestions. Nicely played.