I think it really comes down to a matter of preference. This looks interesting to me, and it caught my eye when I saw it on Hacker News much in the same way Meteor did when it came out. For me personally, it just passed the initial smell test really well.

In terms of some concrete attributes which I like, I think it probably is the best framework I've seen in terms of the general aesthetic. I have high hopes that it will allow me to create most of the view elements I'd need to prototype in an incredibly short period of time. I haven't used jQuery mobile for some time now (> 1 year) yet it seems like there are more CSS classes in Ratchet that mimic the iOS look and feel well enough that one could develop a full iOS app prototype in a day or less. If I remember correctly from using jQuery mobile, there was a bit more code to write, and the general look just didn't feel as good to me.