I've started playing with it a bit. I can see why there are mixed opinions on the software. It definitely feels like there has only been one or two releases of the program. I've played with it for about 15-30 minutes now, and I can see the advantages, but I feel that the interface is a bit clunky.
It has an interface that allows you to keep documents organized. You open up the software and it acts like a Trapper Keeper (for lack of a better word). Inside you then have your folders for various topics. They start you out with a classes folder, personal folder, and general folder. These folders then have sub-folders. So inside classes, you could make a folder for Torts, another for Criminal Law, and more for your other classes. Inside those folder you create notes. Those notes are date and time stamped so you know when they were created. Each note may be multiple pages. Only the original note's creation has the date/time stamp.
The notes feel like a mixture between a paint and a document program. You can free-hand draw with the mouse. You can write in text messages on the page. You can also import data from files such as pictures. The text and drawings can be placed anywhere on the page. That's how it is like Paint. You can take the mouse and click the cursor somewhere to create a new textbox. Each item you create can then be moved around afterwards, as well as modified.
It is this heirarchy structure of notes that I see as being the advantage of One Note. You don't have to make up your own folder system. With One Note, it is more difficult to save class notes in some strange place you can't remember. The searching feature is also nice. When writing things in Word Docs, they are saved as binaries. I don't know of any way to search for specific text in multiple word documents without opening them all and doing individual searches. There might be a way, but I don't know how. With One Note, you can perform a search across the entire "Trapper Keeper."
The interface doesn't feel right at first. As I said, it feels like a clunky combination of Paint and Word. I had to force myself to sit down and use it for a while before I got over the interface feel. Even at that point, I could only do basic things. I've tried controlling how the thing is organized, and the interface is just not intuitive about how I get back the notes that I "Closed." I don't know if it is possible to get them. But they use "Delete" all over the place, so I didn't think that Close was the same thing.
I think that the organization it provides, and ability to search across documents may make this worthwhile. If you're going to be getting this for note-taking, you definitely want to buy it and play around with it a week or more before class starts, so you can keep effective notes, and don't accidentally permanently delete some important notes.