As far as progression goes, most (if not all challenges) are pretty easy. Like, the hardest one right now by far is the hydrologist fight. It's one of those fights where you need a decent amp and a decent team. These challenges should not be behind a massive time gate and with that being said... I hope you don't have orb heists challenges. The rewards from the tiers are nothing special, they are okayish.
The big problem I see are wolf creds. There's a total of 300 wolf creds to be made in this "episode" or "chapter" or whatever you want to call it. Presumably, I've heard that after getting the 300k needed to complete the episode you will instead get wolf creds for your extra standing. Now, I don't know how many wolf creds you would be getting after that but you would need a substantial amount of wolf creds to make it even similar to the rewards you were getting from alerts.
The nice thing about alerts was that while you might have not gotten the things that you wanted, the alert system would be always giving out plenty of rewards. Here, have this alternate helmet, a nightmare mod, nitain, a potato, a weapon, an aura, a skin, some oxium, etc. It was always giving out stuff. I might have not needed some but it sure felt nice exploring the rewards that i didn't need. Now, with the amount of wolf creds to be obtained and the prices of the stuff there I just feel like you just took all those potential rewards from me and limited me to a certain amount of purchases.
I would very much like to see auras/potatoes behind daily challenges. You can keep them in the cred store as well but I would also suggest cutting down the prices on those 2 items. Also, the prices of the alternate helmets are ridiculous as well. I don't know how many times I saw these helmets on the alert system and I deeply regret not getting them when they were available there.
So, in short, I have no objection to your seasonal rewards and most of your challenges (so far, again, please no heist challenges) but as far as auras/potatoes/nitain/alternate helmets go, the old alert system was way more rewarding even if you didn't get exactly what you wanted. To me, this system went from giving out almost everything you wanted minus a few important things to a system that limits your rewards in favor of being able to get those few important things that you wanted.