I'm not familiar with Discworld either (yes yes, bad geek, I know), but I still think that's a pretty nice looking map. The colors are great and the rhumb lines are really neat. It does look a touch too digital for my tastes, I personally think it would benefit from a stronger paper/parchment texture (but then again, I'm the kinda person who always stuffs at least 7 of them on one map).

Aside from that, a pretty great introduction. Welcome to the Guild! Have some rep.

Oh, BTW, I checked out your dA page. Those are some pretty cool props you've got there!