One thing I realised is that there was no cards with co-op boost awakenings this time round and I'm noticing less of that nowadays whereas the killer awakenings continue to be promoted. Some of the more interesting cards introduced are the Green Dark Kali and the Blue Green Sakuya.
Green Dark Kali is probably better as a leader (very similar to FF Lightning's) than a sub although she has the same Dark Kali active skill because she does not have the awakenings of Xmas and the original Dark Kali. I think it is still strong and definitely usable but the other set of awakenings is definitely better utility-wise.
Blue Green Sakuya is available in the MP shop for 300K MP. I will be very tempted to get her if she was unbindable and has Awoken Sakuya's bind clear active skill as I do not have Awoken Isis. However, she only retains the leader skill so I don't find her worth getting.
Overall, I find all the cards having great artwork, with some being hilarious so do check them out, but as usual, there are no must-haves as with most special REMs.