I've been drawing with a mouse for years, myself! I don't think it's that difficult, though it can take a bit of patience. I definitely use the undo command quite a bit, haha.
One thing probably worth mentioning is that drawing with a mouse requires a lot of minute hand movements, which can lead to cramping if you do it for too long. So it's a good idea to take periodic breaks and maybe do some hand stretches if you feel like you need it. (I guess this isn't entirely unique to mouse art, but still!)
@Radeou mentioned vector art, which I can echo since my comic Aiiro No Kunoichi is all done with a mouse in Adobe Flash. I love vector art because it gives me really clean linework, and it's easy to adjust and resize things as needed. That said, it's also got a very different workflow from other art programs, and it can be pretty time-consuming getting the exact curves you want. (Also, as mentioned, there's no blending.)