First impressions are that its simple to blog from. The only real danger I foresee is the peril of autocorrect!
I can easily start and type a new post, I can add a picture straight from my phone, (though I'm not sure where in the post the picture will appear) I can format things...
Looking at the previous posts screen however it seems that some of the times created (which is used as sort order) are not correct, and I can't seem to look back more than about 20 posts, but that aside, as a fast, on the go blogging app it looks pretty good. So you may get more blog posts from me (you knew there was a downside)
Oh one more test, adding a link ed balls
Things it still needs are, a link to a stats page or "number of views" in the Posts page, and a way to moderate comments direct from the app.