Mine is getting started on DPN's. Once I have it going I am okay, but I hate the starting, counting out the sts and the way my needles want to go every which way.
I also don't like to graft, only because I always seem to lose my place, even with that mantra "k,p,p,k." It gets so damn confusing for me. I think I just haven't had enough practice.
As far as something that seems so challenging that I haven't even tried it. . .that would be intarsia or Fair Isle knitting. I love the way it looks, but I just am too scared to try it.