This program has completely captivated me in a way that very few others have. For years I have tried every personal information manager, and mind mapping, and file management tool I could find. At first I found it a bit awkward, but as I used it it quickly grew on me--so much so that I upgraded to the Pro edition (at first I thought I'd just stay with the free edition...). Here's why:

- The learning curve was surprisingly fast. I didn't expect this because the app is still relatively new to the Mac and there are some very un-Mac things about it. However, after a few initial puzzles, I quickly found myself breezing through reorganizations of large clusters of thoughts, establishing relationships with things far separated in the network (hierarchy doesn't really apply), moving files into and out of my Brain, gathering quantities of data (links, files, images) from the internet and keeping it all manageable, viewable, and most importantly, findable with very little effort.

- It actually allows me to organize thoughts and files the way I think rather than the way the operating system thinks. Establishing and changing relationships among thoughts is easy and fast. Though it's possible to mimic conventional, two-dimensional mind maps, this is not what PersonalBrain is designed for. In cases where full control of the visual presentation of information is key, I use other apps to create documents which are then stored inside my Brain.

- At first I didn't like having 100% control over how the information was displayed on the screen. Now I am continually delighted and relieved not to have to deal with this sort of thing. Whenever you activate a thought, the entire display shifts around so you can see as much of the structure as you want in relationship to that thought. In the fully expanded view you can move things around a bit in case an area is extremely dense with thoughts, but I am finding that the more I use PersonalBrain and refine how I establish relationships, the less I need to do this. The beauty of not controlling the layout is that you don't have to maintain the layout--PersonalBrain takes care of it elegantly.

- The biggest drawback to PB lies in some of the un-Mac-like aspects of the interface. It's a very small price to pay for functionality which, for me, has replaced several other apps. The developers are putting a lot of attention to the needs and concerns of Mac users, so this area will only get better.

- The learning curve would have been even faster if there were a really good manual for version 4 (there's a manual for version 3 and a "transition guide" for version 4). Hopefully they will finish the version 4 manual soon. (8/31/2007, Version: 4.0.8.9)