In terms of rewards? Remains to be seen. Quoted “gem value” makes me understandably nervous, as every time they have done this in the past was in an attempt to hide a gem nerf or just a nerf to collection building resources by shifting that “value” into trivially farmable resources that mean next to nothing or actually nothing to a good section of the playerbase. We do know that the system delivers at least some baseline of gems, though, for very little effort, and based on their engagement numbers with the old system, the majority of people are going to have slightly more gems on hand by the end of the week than before (at the expense of some gem and event keys, maybe). Looks like the rewards that you do get are generally delivered much faster than it would to deal with daily tasks, with the exception of Kill 150 (color) enemies for 100 gems, that is significantly worse effort-to-reward ratio than any kill color snotstone event ever was (just check this week, for example, for what you can get for 180 kills of a specific color) with the benefit of the kills not being mode-restricted and maybe having this condition appear more than once a week. There was never a single week where I got all of the rewards on daily tasks and snotstones, but it looks pretty trivial to do here (except, again, in the case of the 150 color kill grind).
In terms of gameplay? I consider it completely reductive. The whole system is just daily tasks for getting you to put in time daily, for which there are already multiple systems in place. Yes, I understand they did this to have a tighter conditioned behavior loop, which means more people will engage with the system. But nothing incentivizes novel team use on a regular basis anymore. The old task system had a lot of terrible, time/reward negative tasks, but otherwise had rewards spread out in a way that gently encouraged use of different teams for a bit of extra stuff, which not only encouraged some team building but optimization of said teams. And yes, this is what the raid/invasion/ToD events try to do, but they also quickly scale to the point where “novel” teams are unviable and the “good” team you are using has far overstayed its welcome, whereas most old daily tasks (most combinations of old daily tasks) had some PvP viable combination that you could switch off of just as they started to get stale (15 battle tasks were stretching it, 8-12 was about the sweet spot). And yeah, I know, this is the part of it that people that didn’t like the system particularly didn’t like, but I already miss having it there. I check all four accounts, and the most “interesting” thing I see is that I can grab a few gems, maybe.
Basically, Adventure Board seems more like a semi-random daily reward delivery system than “gameplay”. Even if I get more gems out of it long term and spend less effort on the rewards that I do get, and I’m sure I will grab most of the “free gems” rewards, I still don’t really like it.