OK, it doesn’t really, REALLY suck, but one really important part of it does. Image handling.
And it sucks massively.
Say you want to put an image in a post. One image. Just that, nothing else.
One like this, which is called test-1.png.
Here’s what WLW uploads for you:
And it’s not even smart enough to use the original filename for the one it shows in the post, no, it links to that one with one called “thumb”.