I would say the market implementation of Dune could be better.
But I haven’t played all that much. For comparison, it took me about 20 to 25 games of Hardback to find a strategy I deployed in my last game that won me the game through market manipulation (I think it did, I won with 80 over 44 points). But then I think Hardback is a great example of a well-implemented random market (as stated above).
So the Dune market stack has only 67 cards over all. 12 of these are unique cards representing important characters from the books like Duncon Idaho, Lady Jessica, Chani etc. Some of these are associated with one of the 4 factions. These are the cards you really want. They are powerful and have interesting and often unique effects that can make your game. If the Kwissatz Haderach is a balanced card is a discussion in itself… The rest of the cards are distributed somewhat unevenly among the four factions plus 15 neutral cards. A lot of these cards exist twice but even among the “lesser” cards there are a few unique offerings. I think it really helps to know what exists to be able to know which to buy and where to go from there.
There is a small static portion of the market with a Verlegenheitskarte if nothing else fits to improve your influence. And there is a VP card (like the tomes in Clank!).
Sadly, there are no cards that interact directly with the market (as the red suit does in Star Realms or the blue suit in Hardback). There are no rules in place to deal with a bad offering of the market.
Overall—I think—this is a game in which you want a small deck that does exactly what you want and you want to cycle through it quickly to get to you few key cards. On the way to this deck you may have to buy a few fillers you need to get rid of again. There is a reasonable number of opportunities to deconstruct your deck or draw additional cards so that in turn mitigates market choices a little bit.
As stated above, I prefer random markets that allow the player some interaction with the market besides buying cards. On the other hand the number of cards here is so small that I feel it is entirely possible in a 4 player game to buy/trash all the cards. (as in Rocketmen where the offering of cards to buy is even smaller).