I use a pair for hihat and ride spots. I also have a pair of KM184s. The c1000 seems to be less sensitive than the 184's but sometimes thats a good thing. I use them on hats and rides as they seem to reject snare leakage better. I have used them on overheads when I do a band off the floor as it doesn't pick up as much ambient room sound as the 184's, you know, the grunting, foot pounding, pick sounds etc.
I use them for overheads (they can be a bit too "sizzly" if you're not careful) and for acoustic guitar (get very good sounds here, lots of positive feedback from players). For the same money or less, try an AT3035 for vocals.
It seems to have become mandatory to bash the C1000, so I'll counter this:
Using the C1000 for drum overheads gives you a kind of Eighties sound, which may or may not be what you want. Apart from that, the fact that it can be powered with phantom or battery makes it useful in a lot of applications. In my experience, toms always sounded rather thin in the C1000 overheads - which might not be a problem if you close-mic the toms.
There are other microphones in a similar price range which you might consider, as others pointed out. You might give the sE 1a a try.
I have used them for overheads, and basically agree with the previous posts (And I though I was just a little nuts).
The mike can seem a bit harsh if it is positioned too closely to the kit, especially the cymbals. I would recommend them if you kept some distance. They can be used in a variety of applications, but results may not be consistent. You might want to borrow one before making a purchase.