I normally like to be quite specific when reviewing software, and I'm still under NDA regarding Lonestar, but I can make some general comments safely: the handwriting recognition in Lonestar is transforming the way I write. It's a combination of three things: dramatic improvements in handwriting recognition (I doubt many people could read my cursive version of the word "hemorrhage"); the ability to rapidly correct text using a variety of mechanisms (choose an alternate recognition, change individual letters, scratch out and write anew); and a writing window / area that expands as you finish a line of writing.
Writing with a pen bestows a physicality to every letter, makes every word a small unity of expression. The Wacom digitizer tip has a scratchy resistance that's remarkably like the feel of a fountain pen (albeit in an ugly plastic barrel that's too thin and lacks heft). While the keyboard is great for keeping up with a rush of thoughts, a pen is by far the superior instrument for deliberate writing. (Also, for editing -- the Tablet OS already supports the gamut of proofing marks but I'm afraid that we'll have to wait for Word 2006 or some bold entrepreneur before the momentous marrriage of the blue pencil and WYSIWYG.)
A couple months ago, I wrote an 800-word column in longhand using Microsoft Journal; about 10 separate Journal pages (the resolution of the Tablet PC and the parallax challenge of the display forces you to write two or three times larger than how you would on paper). Suffice it to say that transforming the result into a Word draft was a considerable task. In the past few weeks, I've written more than 10 times that length directly into Word with scarcely a bobble (by far the greatest annoyance, and one that I hope will be cleared up before Lonestar is released, is that a space is not automatically inserted between the last word on a handwritten line and the first word of a subsequent line).
Lonestar, when it becomes available, will be a user-installable patch. The alpha is tiny -- about 10MB. If you're buying a laptop, you're nuts not buying a Tablet PC.