First impressions...
1. The damn thing is just cute.   Not a word I normally use, but I can't think of anything else to describe it
(and I'm trying not to use the words "form factor").
2. That's Our Boss(TM).  Those of you describing that Boss tone aren't wrong -- it's definitely there. 
Not nearly as bad as the COSM stuff, but even my first experience with the X amps was meh...
Fractal's amp modeling is just clearly superior;  the FM9 has spoiled me.
I noticed LT was using hi/lo cuts;  I'll be trying that.  And to be fair, I haven't tried dialing in any of the amps yet.
3. Pretty decent array of presets;  I tended to like the cleaner ambient stuff (esp. on the neck pup of my tele deluxe).
Some of the FX-heavy ones were inspiring.   And some of the presets are surprisingly complex.
4. The acoustic sim seems noticeably better;  that might turn out to be a pleasant surprise...
5. Had read the manual, but the thing seemed pretty intuitive almost immediately.  I like that while it has
a touchscreen, you aren't forced to use it. 
For me, an awesome upgrade to the GT-1.  
But it's no FM0.