Hard on the heels of iOS 4.0.1 and 3.2.1, Apple has released, a minor yet welcome update to the free EPUB and PDF reader for iOS devices. From our perspective, the most important change is that iBooks 1.1.1 on the iPad now handles PDF links properly when the iPad is in portrait orientation, which wasn't true of version 1.1. (Very shortly after the 1.1.1 release, Apple released 1.1.2, saying only that it fixes a problem with updating iBooks itself.)
Other improvements in iBooks 1.1.1 include the capability to zoom images within EPUB-based books by double-tapping them (after which you can pinch to zoom further; this worked in PDF before), support for ebooks that include audio and video (we suspect this works only with EPUB-based ebooks, but we don't have anything to test just yet), and the capability to look up definitions to English words inside EPUB-based books that lack a specified language.
Along with the PDF link bug, Apple claims that iBooks 1.1.1 also fixes a bug that could prevent some book downloads to fail to complete, provides performance improvements when reading PDFs, and "includes many stability and performance improvements." Honestly, I can't say I'm buying it - if anything, PDF performance seems worse, with pages drawing initially fuzzy and then becoming crisp a second later. It's almost as disconcerting as the Kindle's page blinks.
Alas, several glaring holes with iBooks remain unfilled. Most notably, iBooks still lacks a Back button or gesture. If you tap a link in an EPUB or PDF book to navigate to another part of the book, there's no way (short of setting a bookmark before you tap the link, which is wildly clumsy) to return to the page containing the tapped link quickly. Also, if you zoom in on a PDF page (necessary on an iPhone or iPod touch), iBooks forgets your zoom level when you move to another page. I realize I sound like a broken record, but continues to outperform iBooks in both these areas.
Like all iOS apps, the update to iBooks 1.1.2 is available by clicking the Apps category in the sidebar in iTunes and then clicking the "X Updates Available" link in the bottom right of the iTunes window. Or, open the App Store app on an iOS device and tap Updates in the toolbar.