I really like the XS.
Granted, I think it would have been nice to have it come with some kind of attached keyboard controller, OR, like the 2 previous FR synths, it's own sequencer, but none the less, I really like it.
What's nice about synths like the XS is that it's so hard to judge where they stop. The default architecture of the thing is nice on it's own, but the amount of possiblities really are potentially limitless when you consider what can be added to it or what it can potentially add itself to.
Route a guitar into the Osc Modulation and use a guitar to modulate Oscs A and/or B (and C). At such a point, is it a synth, or some sort of weird effects processor?
Oscs A and B can both go 5 times or more below or higher than the human hearing range...and considering how they can be routed...are tonal sources? Are they LFOs? Etc.
There really is just a large amount of ways to approach and view the XS...at any given time what exactly it is can shift (potentially greatly).
As I noted I just find synths like this really fun, as there's so many ways that they can be approached.
Jared (of FR) really did a nice job in taking something that seems very 777 like in it's base nature but adding a ton of flexibility to it.
The build quaility, as with all FR products I've encountered, is quite solid. And just in general, I really have no complaints.