I admit that I am a "CRIMP-er" (Compulsive Reactive Information Management Purchaser). However, after every software package that I've ever looked at, I have always ended up back to using
the venerable old Keynote, which has been around since the last century! (heh.)
From what I've seen of Action Outline, it doesn't look all that different than Keynote, except with an up-to-date appearance, and maybe some fancier word processing. Keynote is free, whereas the Lite version of Action Outline (which is presumable free, too) places some limits on its use that I could not live with. As for the Pro version, looking at the screenshot and comparing it to the old Keynote screenshot, they look shockingly alike, except that Keynote still has the old Win98 look and feel. Action Outliner is better looking, that's for sure. and there is a lot to be said for a good looking program. After all, who wants to always experience a mental cringe when opening up software that you deal with daily.
In my opinion, Keynote's one real limitation is that it can't collect Word files, or PDF documents or websites very well, and perhaps Action Outliner does this better. Keynote can only link to these document files or sites, but it can't display them, and some people want to be able to see the entire body of their notes collection within the confines of their software, rather than to have to open them up in external applications. Keynote's limitations are perfectly fine for me, since I write a great deal of my own notes, and only occasionally link to a website or an external document.
Keynote, and presumably Action Outliner also, have a very quick learning curve. I've also been looking at
General Knowledgebase (to help organize all the various help files I've built up over the years for all my computer software and hardware), but it's been complicated to learn, which discourages me from opening it up as often as I should. By contrast, with Keynote I was up and going right away, and presumably Action Outliner looks to be just as easy to learn. (I'm the kind of person that doesn't take kindly to struggling with the GUI on software, and just wants to be able to get on with whatever it is that I want to do with the software.)
After spending years looking at outlining and note taking software, I'm convinced that they're valuable, but I'm also convinced that the value of each software application is completely subjective AND also dependent on the type of project for which they are being used. Some people are perfectly content with a simple Notepad document, others like a system that combines with their browser (Evernote, Google Notebook), still others like a system that interacts with Office (Microsoft One Note). Some like a wiki style note taking system, which allows tagging, and others like a simple outliner, or outliner with tabs, and yet others like mind-mappers.
Furthermore, if you're taking notes for a dissertation or for something of a scholarly nature, then you might want something that's better at tracking not only the information but the source of that information. If you're simply looking for something that tracks the flotsam and jetsam of your life -- ie miscellaneous project ideas, contact info, interesting avenues for further exploration, etc. -- then a simple listing in some sort of long text document might be sufficient. So not only is the value of note taking software dependent on each person's style of thinking, but also on the purpose of the information collecting. All this makes selecting note taking software difficult and subjective.
The good news is that there's at least one of every different kind to fit EVERY budget, from no-cost to extremely pricey (and which comes with commensurate hand-holding and support), and every style of thought-processing, and for every kind of need.