Might be the best annotator

GoodReader is a great app for annotating PDFs, and a good app for reading them.

The app receives frequent updates and improvements. The developers seem to understand to a large extent what users of such an app might need to do, and what the best possible way (given iOS restrictions, I presume) to do them are. As a result, its quite functional, and the interface makes sense. (Those can be really complicated in annotating apps.)

The cloud sync function works well. Now it works in the background as well. One *must* be able to access annotated versions of his/her papers anywhere!!! (This is why I bought an iPad to begin with.)

There is no quick-access brightness setting for the entire screen, but there is a quick-access contrast setting for the displayed pages. I kinda like it.

The squiggly note function with the zoom-window is indispensable for me! It was probably one of the main reasons I chose this app over others. It is great, but after you made your annotation, you cant edit it anymore. You can scale it, move it around. But perhaps you want to remove an arrow? I wonder if they can be left "editable." Speaking of the squiggly function, a sexy ink would be super nice! (But not necessary at all, to be honest.)

A very important shortcoming is the following: After you perform a markup, you can open it and add a note. Great. But the presence of an accompanying note *must* be indicated by some small mark somewhere on the markup. One cannot possibly check every markup for potential accompanying notes.

GoodReader shines in annotation, but as far as reading is concerned, its not that great, I think. For instance, after you follow a hyperlink, or use the navigation bar at the bottom, you can go back at the press of a button. But then you might also want to go forward (i.e. back again). That doesnt seem to be possible, and its causing me some trouble. Also, you cannot swipe away partially-rendered pages. Meaning that if you want to swipe forward 4-5 pages, you cannot do it in 4-5 quick gestures, you have to proceed one-by-one. Not that the renders take too long, but its clumsy. In addition, I constantly find myself switching from one page to another because I find the tapping regions a bit too large. The "inconspicuous" center area where you can tap to bring up the main menu is therefore too small.

And finally, the mother-of-all-reasons why its not so great for reading: no continuous vertical scrolling. Imagine the following situation: Equation (5) is derived from Equation (4) under such and such assumptions. So, you want to compare the two equations. Fine. Equation (5) is in front of you, whereas Equation (4) is at the bottom of the previous page. Pretty annoying when that happens. (Which happens a lot!)

I should note that, in my capacity as a physicist, I am using only a subset of features. There are features like inserting a new blank page, and more. The important thing is, judging by the way the developers seem to approach their app, one can be confident that GoodReader will remain one of the most functional, most intuitive annotators around, whatever the reason might be for your annotating.

Jemsoyou about GoodReader PDF Editor & Viewer, v4.3.0