I think it is a brilliant product idea. I have not tried the Twin, but I did get a chance to spend some quality time with an Apollo, and the converters and preamps are pretty darned good. About the only other preamp/converter in this price range that is competitive is Prism Audio's Orpheus. So I'd expect that the converters and preamps in the twin ought to be just as good.
Now I have some nice preamplifiers already, but I don't yet own converters that can match these, so I will be watching. If history is any indication, Windows drivers ought to be available before too long. How long is too long? Beats me!
I do have a couple concerns that I'll mention just in case anyone else has the same issues:
1) as of today you can not stack different Apollo boxes, e.g. you can't combine a Twin with the Apollo 16 - you can't even combine the Apollo with the Apollo 16. (Well, last time I checked anyway.) That's a problem for me, since there are times when I need 16 - or more - inputs active at one time. There are work-arounds, but I don't like work-arounds.
2) I'm still not sure how useful it will be to have the plug-ins hosted in the interface. It's a really cool idea, and a bit of showmanship to boot. And I had fun with it, but I walked away wondering just how much I'd use it if I had that capability. I still don't know.
3) I am a big fan of UA plug-ins. I turn to them probably more often than anything else in my toolbox. They don't do everything, but what they do is pretty awesome! So what I really need is GOBS of horsepower, meaning an Octo card probably, and that might be a better use of my funds.
Anyway, as I said, I am watching... the Twin/duo would double my current horsepower and add great sounding inputs and outputs for under $1K. That's pretty tempting.