Waaaaayyy too many limitations. The demo is worthless because you can't save, preview or publish your blog - so how are you supposed to see what it can do???
It's tied to hardware, so you can only run it on one machine... well, I have a laptop and a desktop and I don't want to be limited to one machine to blog. Plus, what happens when I want to upgrade my machine?
Adding paragraphs is a bit of a pain, and multiple help tabs is kind of redundant. The themes are almost all the same.
The real killer is that you're stuck using it with .Mac - which turns away about 90% of their potential audience right off the bat.
On the bright side, it's a great looking app, and show a LOT of potential. I'll be keeping my eye on this app, but until I can try ALL of it's features, they aren't getting my $$$$.