Now that I've finished Dark Souls, I feel I can give some better input.
The biggest thing I didn't enjoy, was having to look up information on the weapons, their scaling as well as a few of the more obscure mechanics/stats. Having said that, I don't have a solution other than some tutorial boxes/text. Which I don't think work in Dark Souls. Maybe guidance messages?
Otherwise, there were some annoying things, like the bed of chaos, the invisible walkways in the crystal caves and blighttown.
Also, framerate in some areas. Hopefully that's been resolved in Dark Souls 2.