Just finished the last Chaos Rift I'm going to get to do before they're gone...
And honestly? Completely underwhelming. I spent far more units on energy than I have in past events and in the upper tiers of the rifts I got nothing but 1* boxes. I think my total was 3k 5* shards, 1500 4* shards and then a bunch of useless **** from the beginner and normal rifts. I feel like the chance of getting something good was far too low for the attempts that were available to us, and the energy costs for this on top of HAVING to 100% a much longer event quest than in the past was not worth the payout.
In the future I really hope Kabam doesn't do another single RNG based event like this again, it makes your resource spending feel like a complete waste.