For me, the thing that nails me with doing sprites is just how it looks so different when you're zoomed in compared to how it looks when you're zoomed out at 100%. It has that "yeah, this should look right... wait, nope, what the heck, how did that happen" effect. :P

I mean Speed's guides are REALLY good, but I just can't get the hang of it. But yeah, I've been focusing my attention in the drawn art area anyway. I'd probably get it if I just practiced more.