I've been playing FFvix on and off since around the launch, with a particularly long break from when billing began to a few weeks ago (I was on Lindblum, now on Sargatanas after merge ). It has been getting noticeably different (in a good way) every time I check back.

To answer the question about the player market, it's still based on retainers, and selling is really not much different, however it is now much easier to buy: the retainer search now shows you the items of the type you select that are for sale, sorted by price, and you now can click on one and buy it directly from the search. Every time you do buy something however, it has to reload your surroundings (all characters, npcs, etc.) and then you can search for something else, when the menu comes back up.
There seems to also be a limit to the number of retainers that can be in the market wards, as it's been reached with the server merge, at least in Ul'dah.