I got it a little while ago and generally speaking I really like it. I like its flexibility. Unfortunately messing around with the demo for a day or so didn't give me really good insight into how it would actually perform.

Some issues I have encountered:
Slow performance/responsiveness. (1.25Ghz/1.5GB) to bulky for taking quick notes. Could benefit from at least one more level of hierarchy. Now I have multiple docs, it would be nice to use just one.Application preferences instead of document prefs. And changes that apply across the board. I set up one document with a bunch of items on my shelf, only to find this not available in other documents. Did I mention performance? Not so good.

That being said, I really dig the concept and application. Info managers are only useful if you can use them efficiently and Formation allows you to organize your data in a way to best fit your needs and workflow. Despite the slowness of the app, it has quickly become indispensable. I really look forward to Formation 2.