Got to say, this looks absolutely fantastic!
Have thrown it on my phone to give it a try!
Although, without knowing whether it'll do what I'd like it to with multiple hosts, I can't obviously test this on the free version...
I have a number of XBMC instances at home, all sharing a single MySQL database. I have a server, which is always on. Once nice feature of Yatse is that you can specify multiple hosts to use a shared database, meaning that the thumbs etc only need to be retrieved once, therefore reducing the storage requirements on the device, and any library updates are done by connecting to this "server" host.
Additionally, it's unlikely that multiple XBMC devices in the house will be in use at once - having the ability for the app to "poll" the multiple hosts to see which is "awake" (when the last-selected host is not responding) (and, with the option, obviously, to be able to tell it to not connect to the "server" host)
As I also have multiple hosts, when I'm selecting some media (such as YouTube) and want to "Send-To" XBMC, it would be nice to be able to select which XBMC host, rather than just use the currently configured one (if the auto-sensing of active XBMC instances isn't available)
Do you have any plans for making it display a "Now Playing" in the notifications bar, and a lock-screen widget?
Oh, and the touch sounds still play on the initial Select Host screen, even if they're disabled in settings.
Overall - looks fantastic, will need to have a bit more of a play with it - and I know that you're still in the early stages with it.