I'm trying out Windows Live Writer.  Currently, I do all of my blogging via Frontpage, so this will be a shift for me.

Here's what I like that I've noticed while playing around writing this entry:

1. Looks like it interoperates with my existing blog well. It properly got the blog name and category strings.
2. It has a cute and simple UI. 
3. It has web-preview! This is so cool. It actually shows me what it will look like when it's published, using my CSS stuff and everything. Wow!
4. Has a nice "safe as draft", although I'm not sure where it's saving. Probably somewhere under "my documents". I usually use "save as" to find that sort of thing, but there's no "save as" here. I guess that's part of the simple + cute UI.
5. I can get at the raw HTML. Good...
6. I managed to hit an unhanded-exception error. Hey, it's a beta :)  (hmmm ... I guess no automatic emoticon support.)  It gives me an option to send an email error report, kind of like its own dedicated Watson report. I can actually edit the email before it sends it, so I can comment what I was doing.  At least it keeps ticking and I didn't lose any work.
7. It has spell check, but it's manual. (One of the big advantages over VS's html editor for document-style html). I actually almost missed this. Both Word and FrontPage do the automatic spell checking with red-squiggly lines underneath. I haven't had to manually run a spell checker in years. So having a manual spell checker here is better than nothing, but +1 for FrontPage.
8. It has a "publish draft" option which actually uploads it to the server without publishing. That's pretty neat because it lets me continue to leverage the previous UI.
9. It looks like it gives the URLs good titles based off the blog title, not just random numbers as titles. This is actually one of those less advertised but super cool features of Community Server. I'd rather have a URL like http://blogs.msdn.com/jmstall/archive/2007/03/04/debugging-cmdlets.aspx then http://blogs.msdn.com/jmstall/archive/2004/09/30/236281.aspx. Notice the first URL has a descriptive ending ("debugging-cmdlets") instead of just "236281".
10. It looks like it has easy picture support! This would be a killer feature. I'd love to be able to include screen-clippings, etc in my blog. It's easy to get screen clippings with OneNote, but I currently still have to manually upload the picture somewhere, and then manually setup the link, etc. This looks like I can just paste the picture in while I'm editing, and it magically takes care of the rest.
11. The shortcuts appear the same as FrontPage. Cool. It's very annoying when 2 apps that do the similar things have totally different shortcuts.

Some miscellaneous tests:

Here's  my test of whether it will properly format code snippets:

    static void Main()
    {
        Console.WriteLine("Hello from Live Writer");
    }

This is using HTML produced from my RTF2HTML converter. Looks like it has some issues with the <pre> tags, but nothing that switching to an HTML view can't solve.
 

And here's my test of whether it will do pictures:

(it should be a little blue smiley face)
If this works, my blog is going to get a lot more colorful.