I'm just interested in reading. I tend to not use annotations. I am often trying to understand large technical documents that are not really meant to be "read" from cover to cover. They are more reference material. Thus I ping pong around a lot. I do lots of searches. No one has implemented a RegExp search. A search history would be nice.
I'd like my bookmarks to be per PDF instead of system wide. I'd like some bookmarks as they are implemented as they currently are typically implemented where you put a text "name" to the bookmark but I also want "quick" bookmarks like 1 through 10 where I can put a bookmark on a page with one keystroke and then get back to that bookmark with another single key stroke. Or, better yet, a "tab" appears (perhaps with a page number) ("tab" as in the old dictionaries -- not as browsers call them) so I can click on that tab and go to that bookmark. Thinking in terms of "tabs" as browsers do them, allowing me to view the same document in multiple windows (or multiple tabs) would be nice.
I like my Nook's "Furthest page read" feature where the rare times where I am trying to trudge through the whole book, I can quickly resume at that page.
I'd like some type of "bread crumbs" so if I go from page 82 to page 182 (either from a search or by typing in a page number), I could go back to the page I came from. In Emacs, they have a history of "marks" where you can move forward and backward through the history.
Adobe's Reader (as is true with any Adobe product) "feels" overweight. It feels very corporate and very non-Apple. Plus, again, it has features that I can't imagine anyone really using and lacks features that seem obvious to me.