Apple just released an update of its very nice iBooks.
The Kindle still is my preferred ereader for personal reasons, but I prefer to teach with iBooks.
Last year when I taught a literature survey, I experimented with asking students to use out-of-copyright free etexts, and to annotate them in iBooks. The fact that iBooks lets students annotate texts in different colors was very useful as I was introducing the class to college-level close reading, but I did find the interface a bit tedious.
Once students got the hang of close reading, asking them to continue to mark up their texts seemed to be too demanding, since the iBooks interface was a bit clunky. It took longer than it should to switch colors, so I often found myself not bothering to highlight, since holding down my finger in a word, waiting for the highlight option to appear, and then clicking the highlight button, then selecting a different color (by clicking on the word “yellow” or “green” or whatever) was just long enough to break my flow of concentration, and much more cumbersome than simply circling a word or making a stroke in the margins of a print text.
The new interface makes highlighting a bit smoother. Being able to click icons, rather than having to read text menu options, helps me to stay mentally in the text.