I was excited for the Challenges to finally exit beta, and while I appreciate that they're truly daily now I have to say that I don't enjoy the system as much as the previous one and I'm doing them a lot less.
The idea of being able to choose our own sounds nice, but I've ended up feeling more restricted. The new challenges are as specific as missions, whereas I liked that the old challenges had more leeway. They offered a bit of direction without telling you exactly what to do. One restriction other than passing the harvest check is fine, but some of these are telling me species, map, and time of day. They're making the choices for me, whereas the old ones were more like gentle nudges.
The fact that the old ones were tiered was also better: even if I didn't have time to do the whole thing I could do a tier or two and leave with some rewards and some sense of accomplishment. That the new ones are all-or-nothing feels like a downgrade.
If you want to have as many restrictions as you currently do you should do a hybrid of the two systems and tier the rewards. So the base objective should get you a small reward, and then you can add on to that by doing it with a specific weapon type, hitting lung, at a certain time, etc. (This is also how the missions should work, btw).
I would have been perfectly content if instead of a total rework you'd just taken the beta challenges, made them daily, and added more of them. There wasn't really anything wrong with how they worked.