I haven't played with emotionally mindful yet, likely because since I rotate, I don't have as many sims who accrue lifestyles.
I do really like the sentiments. They are random and different so not all relationships seem the same. You can pursue a sentiment or let it be. I find myself wondering when some sims are going to get sentiments from interacting together but being surprised is a good thing. It's also interesting that they fade and you can either view that as significant or not.
I mostly see sentiments develop between family members, romantic interests and close friends. It adds another layer to dating for the sims because I can take the sentiments into account if a sim is trying to decide between several. I've seen some one-sided interaction. I've also seen different types of romance which is noticeable when you rotate. You can decide what type of relationship matters to a sim.
There are also more complex family dynamics from that. For example, I have a household where the dad clearly bonds with the daughter and the mother bonds with the son. That lets me come up with a more complicated family dynamic. They're a happy family but some people are closer with each other than others. You'll also see sentiments develop as family members interact even when they live in different households.
It's a good change.