Honestly, looks like wasted money to me. It's completely digital, you don't seem to be able to add your own samples to it (which kind of defeats the fact of going digital), synth sound seems to be fixed... dependIng on the software you have on your computer, i think you 'd be better off with a good hardware controller for the software on your computer, that fits perfectly with your work flow and which you can use to opperate and tweak any sound or sample on your computer. And because it (this Circuit) is digital, it's not adding anything beyond what's available in software on your computer already. So unless you just want to play around with it on places where you can't bring your computer and like to turn knobs, sure, then it might be useful. To serve as a box to try out some new ideas... sure. If you want it to complement the sound you already have, this isn't it i'm willing to bet. But then again, why not get something that does both?
Now, i'm not saying you should dish out 2000 bucks on a Smith/Linn
Tempest, but seeing as the fact of going digital doesn't scare you off, maybe look at the
LXR, which is an opensource drummachine but you can load your own samples to it. It seems to be very interesting, though i haven't worked with one. And cheap to boot. Or get something of (completely different) analog gear in the pricerange. Novation Bass Station isn't much more expensive (but ofcourse it's something completely different than this Circuit), Arturia Mini- or Microbrute, or save up a bit and go for a new Moog Mother-32. Waldorf Pulse 2 is undervalued, Doepfer Dark Energy 2, Korg MS20 mini... All gear that won't cost you an arm and a leg, but completely different from what you're looking at right now though.
Also don't forget that there is a vast offer of second hand stuff. For $320 you can already get some nifty toys. This Circuit seems to offer all of the hassle of analog equipment but none of the positives of going digital. I think you need to get yourself some good earphones, and do some googling and youtube listening (HD) to see if there's nothing out there that really offers a sound to complement what you already have. And if not, if you wouldn't be better off looking for a controller to add to your workflow. Or at least read up on whether or not it can serve as a controller as well. At the very least. Or take a look at the
Maschine Mikro or
Beatstep pro.