There are a few new blog entries at the web site
https://blog.getremarkable.com/
From an ebook perspective, they're only supporting PDF and ePub, and only DRM-free PDF and ePub at that.
It's definitely aimed at people producing their own documents, IMO.
I'm interested in their use of a non-glass substrate in the display. But it's definitely not something I'll be ordering until it ships. Note that your card gets charged when you order, not when the product ships.