While the camera has a few interesting quirks, including a smaller-than-APS-C 1" sensor, it is one of the few from Canon that can actually shoot 4K internally — and at a high bitrate with Canon Log built-in. The XC10 has sort of fallen into the trap of not being a well-defined model, as it's not really a cinema camera and not really a fully-featured documentary camera, it's somewhere in the middle. It's better than a DSLR for shooting video but has a smaller sensor than the cinema cameras — though the company has mentioned a number of times that they see it as a possible B-cam to their C100/C300/C500 camera line (and as a possible drone camera, but it doesn't seem like it's particularly well-suited for that).
Having a smaller sensor does make focusing a little easier for documentary work and allows for a fixed lens with a wide focal range to fit into a small package, but that lens is not a constant aperture and limited to just f/2.8 wide open.
As for what the camera is capable of, Johnnie at cinema5D took the XC10 for a spin when it first came out:
CFast 2.0 cards are coming down in price all the time, but it's just another part of the package that has turned some people away (you need those for recording 4K). Either way, if you've been interested in a camera that can give you nice images with high bitrates, and has better quality than a DSLR in a similar package, this one just got a little bit cheaper.
Just for fun, Redrock attached a 35mm adapter to this camera a few months back, and the results are interesting. With a little more tuning, it's not impossible to get what I think is a completely unique look, due to the variation of the rotating ground glass of the adapter:
Source: Canon XC10