NotePro sounds like a notepad replacement, a simple text editor, but it is more like Write on steroids--or perhaps Word on a diet. It offers a useful Multiple Document Interface environment (or a tabbed one, if you prefer) and a wide range of helpful features such as styles, a built-in calculator, tables, spell checking, and so on. Of all of these, it is the styles feature which really makes it useful for moderate-length documents, and is a major step up over its free competitors.
NotePro has many of Word's features for about one-tenth the price. The missing features will be the deciding point for many users. While not an exhaustive feature comparison, it lacks advanced formatting such as columns, or large document features such as footnotes, automatic table of contents, or indexing. This is not a criticism, but a caveat: NotePro is not a cheap Word replacement, and it doesn't pretend to be. If you actually need the "power user" features of Word, this won't do--but most users don't, and they won't miss their clutter and confusion.
Performance-wise, I found NotePro fast and agile, even with several documents open. The interface is very standard, perhaps a bit cluttered with buttons, but most programs with this many features are, and I prefer seeing all my options to Office 2007's confusing and unintuitive "ribbon bar". Your preferences may differ.
If you already own Word and a comfortable with it, NotePro probably won't appeal. For those without Word, or who find it still too bloated and confusing, this is an excellent tool. It can save in Word 6 or Rich Text Format, making it an inexpensive replacement for Office for users in corporate environments whose word processing needs are relatively low.