I think their original songs are pretty damn good, especially Romance and Path. I'm not too fond of thier covers though, they should just write their own stuff. I have high hopes for their next album, since it is going to be all original material. There should be more "dark modern classical" bands (or whatever you want to call them).
I have only heard a couple of their covers. I think I ought to check them out some more though. If you can play "One" on four cellos and make it sound remotely like the original recording, you deserve some credit.