Thanks for the link (you might want to change it to http rather than https, it appears their site certificate is invalid and gives a warning - a http link goes straight through).
I'm not a Mac user, so it's not much good to me.
They don't give away much detail about what the software actually does on the website - so I'm not even sure if I might wish their was a Windows version.*
Their pricing scheme is interesting. My first reaction is to not like it ... but the more I think about it the better it looks to me. (Correct me if I'm wrong but) It appears you get to use the software for as long as you like, and only have to come up with money when you actually want to start publishing. So if I assume it does something other than take a manuscript and output an epub/mobi (I am assuming that, because it would be way to much money for a simple epub generator), then you get to have a good play with what (to me) are the most important parts of the software before deciding if it's worth the money. If you only produce one book a year (I wish I had the time to achieve that
), then $30 doesn't seem too bad. If you are more prolific, or just really really like it, the $200 unlimited tag doesn't see that unreasonable for such specialised software -
IF it really is that good, which they give you plenty of time to discover.
The first thing I would be looking at (if I had a Mac) is to see what options it has for saving your manuscript. You don't want to spend months playing with a manuscript in the software, decide you don't like it after all, and then not be able to output your efforts into something you can use elsewhere.
* ETA: Actually they do have a link to a "help" page at the bottom, which offers more detail. I must say that the features look a bit sparse - compared to something like Scrivener - no organisational tools at all, but if their editor was good enough it might still be worth consideration.