I just wrote to Apple with an iTunes 11 feature request - view books by category. It seems to be the only issue I've had with a programme that was showing it's age, poor interface decisions and legacy problems.
Hi there - the new iTunes is great, really pleased with how it looks.
There is one quite glaring feature missing when it comes to books, there is no longer a view by category function - which used to be the default?
I manage a few hundred ebooks and I really do need a view by category, in the same way you have a view by author option. I'm sure that users with more than a dozen or so books would hugely appreciate this option and it would make my workflow with iTunes so much easier.
I look forward to this option being available in an update!