Posted my full thoughts in the c/onednd thread. Overall I think it looks better than I was expecting, though I'm sure the internet will find everything deeply problematic with it quickly enough. I think Monks really could have used a prior pass, they're the main one I'm not sold on right now.
After thinking about it, I feel like there could be a nugget of good design in this idea. Obviously the RAW in this UA is simply too much, but if a limiter of some sort is put back on the bard I think there could be something interesting.
For example, if the bard's spell selection was limited to certain schools again. Or maybe if they returned to a spells-known caster. Even then, having access to all three lists at lvl 10 I think would need even further limitations. I'm much more approving of a 'magical secrets' feature more like the current base game, that only came at specific levels, only granted one spell, and was a permanent selection.
I just miss spontaneous casting, rather than all classes being prepared casters... T_T