Kindle for PC also lacks search capability, although a Future Improvements item in the menu says that Amazon plans to add both annotation and search support. (pcworld.com)
The first, called, well, Options, is a surrogate pause button that also brings up contextual info when in the main interface and lets you delete items in the menu. (t3.com)
Another minor nitpick is the missing durability meter underneath equippable items in the menus, making checking the remaining lifespan for your or AI companions» weapons or armour a bit of a hassle. (nosleepgamer.com)