The default skin for Oatmeal is rather fugly, but a quick search through the forums over at KVR will yield a thread or two containing loads of much prettier custom skins. Don't let the first impression throw you off though, it's a hell of a synth. Nitrox and Atlantis are both amazing as well with flexible modulation routing. The sounds I've gotten with these three synths are definitely on par with things I've heard people getting from pricier plugins like Massive. It surprises me a bit to see that these three aren't mentioned quite as much as other freeware.