To sum up what I've seen with the new system:
1) Apparently, trade range is now shorter.
2) I have lowered accessibility to my trade options: I am in a region of my realm, not traveling, and unlike before do not have tools to set up trades.
3) Trade offers must now have a "best before" date.
4) I must now chose the price from a drop-down menu, severely limiting one's flexibility.
5) I can't target specific regions with my offers, I can't chose to favor one buyer or seller over another. I therefore cannot send caravans before food is available, hoping they'll arrive just in time to snatch it when it becomes available before others.
What have we gained? I haven't had much chances to fiddle with the new system yet, but all I'm seeing are negatives...