I played two games yesterday (and lost them) against other people. And also I've playing the challenges. Imo, they still have to improve, I thought they were going to force you play every faction deck with the challenges: ie. NR deck in the NR challenges, etc; but no, it means you play against that deck. Imo it isn't a good way to learn, you don't even have to put attention on what cards the opponent is playing, if you build a deck with a good combo you can win without looking at the opposite side. The AI isn't good enough.
About the changes, they are mostly positive, though with one exception: the weather cards, I feel now they are less strategic, because they don't affect the two sides anymore. They fixed how swingy they were, but now it's just a boring AoE damage over time effect.