Really rather powerful. I've only had a very brief chance to play (busy at the moment), but it's a fully equipped authoring program, from what I've seen, with some really nice features (and it does now have a focus mode, Paul). Seems fairly quick and responsive, too.

Looks like a very interesting alternative to e.g. Ulysses or Scrivener, but with more emphasis on academic output.

I shall play some more when I've got a bit more time.