I was excited to see annotations mentioned in the description of the updated Papers app for the iPad, but was disappointed in the execution. They added two kinds of annotations: text notes and highlighted passages. While both are useful for active reading and appropriate given the characteristics of the device, the implementation left a lot to be desired.
The first problem was that I could not figure out how to create either kind of annotation without first reading the instructions. This was due to their design decision to reduce clutter in the UI (a worthy a priori goal), but given other constraints on interaction, the design required long-lasting gestures (tap and dwell, tap and drag), which are hard to discover and occasionally hard to reproduce.
Each annotation style also has other interaction issues. Notes are created using a Post-It metaphor, which is quite reasonable. Unfortunately, after you are done typing a note, the Post-It goes away and gets replaced by a push-pin, the kind you drop onto Google maps. While this element is fine for marking a precise location on a map, it is not effective for representing a text note for two reasons: text notes are not that localized, and you cannot see the text note without further interaction. In iAnnotate, text notes can exist in three states: collapsed, viewable, and editable. While the viewable mode is not ideal because it obscures the neighboring text — often the very text one is commenting on — at least it’s possible to see quite a bit of both. In Papers, the Post-It view opens too large to be able to view much of the document and the note at the same time.
Passage highlighting is a bit better (and certainly better than not having it at all), but the interaction is, again, not as clean as that in iAnnotate. You have to tap and drag to select a chunk of text, at which point you get the standard text selection handles, which you can use to tweak the selection. Tapping off the handles creates the highlighting marks on the selected passage.
My take is that these features improve the Papers offering considerably, but that the interaction design needs to be thought through better.