It had 4 stages, and the latter 2 involve writing the ebook description and uploading the ebook to Amazon so I'll skip them. The first stage is a basic text editor, and it only works with text files. That first stage is hardly worth mentioning other than to point out that everything can handle text files now, so it really adds little to the app.
But the second stage is interesting, and it potentially has the most value. You're given a split screen view with code on the left and browser on the right. The neat thing about the code view is that you can cut and paste html code into that view from another file. I like to start with HTML, so this appeals to me. You're also given the option of a bunch of standard HTML and Kindle tags (page break,bold, italics, header, etc). You can insert them into the code.
Aside from the stage with the code/browser view, KW is less capable than my preferred method.
Let me tell you how I make Kindle ebooks. I'm used to starting with HTML files and images, and my usual first step is to convert the Word/PDF/whatever to HTML so I can edit it. I'm used to editing the HTML by hand, and at this point I usually clean up the excess formatting and then add the basics (page breaks, link anchors, etc). I also add a reference to one of my stock CSS files.
I then fire up Mobipocket Creator, and I use it to add the metadata (author, title, publisher, etc), create a TOC, and add the cover image. I like Mobipocket Creator over Kindle Writer because:
- it has a metadata editor as a separate menu;
- it can handle multiple files;
- it also has a TOC generator as a separate menu; and
- it does error checking for me (bad links, missing images, size constraints, and much more).
I also like Mobipocket Creator because it can do tricks in the spine file that Kindle Writer cannot. There are actually a whole bunch of subtle features that Mobipocket Creator can add to an ebook that aren't visible on the Kindle, and I like to add them as a surprise.
Okay, I can see that I've written almost as much about Mobipocket Creator than about KW, but that's because one has features that I want added to the other.
Kindle Writer is quite capable but it is still very basic. I would not recommend that a pro buy it; whatever you're doing now is probably better. I'm also not sure an amateur should get it either; I suspect that by the time you do enough ebooks that this becomes a break even investment, your abilities will have moved beyond what it can do.
If the next version of the app refines the code/browser view in stage 2, there's a chance that it will grow into a tool that a pro could use. But it would need to have a better work process and it would need the extra editing menus (like Mobipocket Creator).