I bought it primarily for the adjustable polar patterns, otherwise I would have gotten the C1. I had it for a while without using it much, as I was getting familiar with a pair of B1s and some MXL 603s and that gave me enough to do.
The first time I used it was as a stealth mic to record a wedding ceremony and music, with other mics. It did well for remote ambient micing.
I was doing live sound (and tracking) a concert where one set was strictly acoustic - bass, mando, guitar, dobro, three and sometimes four voices. We set it up at center stage, set to cardioid, and had the musicians gather around in a semicircle facing the audience in the old Grand Old Opry style. I found, as expected, less manageable gain for live sound than the boatload of dynamics we had going for the rest of the concert, and so it was a little quiet. But the sound - OMG the audience was so quiet you could hear a pin drop - and catch it on the track. It was gorgeous and was the first time I had gotten anything remotely like that kind of sound live.
The last time I used it was for a string ensemble concert, again live, but only for tracking. I suspended the C3 in omni mode at the center of the ensemble. We also had two opera singers, so it was high enough to be in the line of fire, so to speak. I also used two B1s and two Neumann KM 185s at strategic points behind or within the ensemble, and a pair of 603s picked up ambient (and a hell of a lot of natural reverb) at the back of the hall. I pulled seven tracks; the most dependable being the C3 because of its placement and type. The others blended nicely, but the C3 didn't miss a thing. It's a workhorse, all right.