I liked the system well enough in Oblivion (and weren't the store owner's disposition towards you would raise if you're willing to sell plenty of stuff rather cheap to them? That was pretty nice, I think). Though I must say that Morrowind's barter system was already pretty good enough as it is in a certain area. It wasn't as tedious as the Oblivion's system, where it would be quite a pain in the [censored] whenever you were about to make a transaction for a bunch of different stuff at the same time (a single transaction at a time for each items. Bleurgh).
What I would really like to see though is maybe an added depth to it without making it too cumbersome to pull, really. So it's a yes for a bartering system, in one form or another but not when it becomes too cumbersome, and a no to making it more like how the Acrobatics and Athletics skills were in the previous games.