I read Omnisubjectivity, by Linda Zagzebski. This book is short (43 pages of actual material), and I wouldn't recommend buying it, for the price. But if you find it at a library, I might recommend reading it, if you are interested in the concept of God directly experiencing the experiences of his creation, from the perspective of a Catholic philosopher. Zagzebski's approach might be a little more to the taste of someone from a traditional Christian background than my own writing is.
It might be good to know that she wrote an essay on omnisubjectivity titled "Omnisubjectivity" in Oxford Studies in Philosophy of Religion, volume 1, ed. by Jonathan Kvanvig. This also looks like something I would prefer checking out of a library to buying.
In this review, I focus on how Zagzebski's project interfaces with my own, or gives me reason to connect with some of her "news" (she brings up issues that come from the world of classical theism).
I don't think that Zagzebski would have reason to object to my philosophy, at least in my basic project where it might overlap with hers, because we both affirm that omnisubjectivity is something that does not involve God being identical to the consciousnesses of creatures, of which he has subjective knowledge.
In her understanding, God makes a constant renewal (my words) of his awareness of other beings, like we do when we practice human-scale empathy. He experiences what he's experiencing, rather than what we are experiencing, but his experiences are (perfectly) faithfully copied from our own.
In my understanding, God experiences the exact experiences of his creatures, but is different from them by experiencing more than those exact experiences, including some which are private to him. God is able to be himself by being more than our consciousnesses -- a certain kind of distance made possible by being even more conscious, rather than less.
Zagzebski defends her theory from the idea that God is made a sinner by being subjective to our sinful conscious states. I would defend my theory by saying that a person is sinful based on their disposition or heart, not based on their experiences. If a demon overtakes a person and causes them to be angry, it's not necessarily because the person really wants to be angry, and that shouldn't count as sin -- it doesn't in God's eyes, although humans may still be suspicious.
Zagzebski brings up counterfactual subjectivity. Is it possible to experience the experiences of people in possible worlds? I hadn't thought of that possibility. Is it necessary for an omniscient God to experience the experiences of every counterfactual consciousness? For today, I will say that I favor saying that possible worlds only exist as imaginations, and therefore have no reality of their own. God need not experience what only exists as an imagination if such imaginations have not been imagined. It might be useful, somewhat like Zagzebski says, to think counterfactually for the purpose of doing the right thing better. If imagining someone's thought process in a human, empathic way is useful, then why not use omnisubjectivity to actually know, rather than guess at, the way someone would feel in a given situation?
However, I do not think that people can be perfectly predicted, because their free will has not acted yet. So God could only guess, and would consider multiple possibilities.
Because the book mentions them, I'll briefly mention the divine attributes of timelessness, immutability, and impassibility. I don't see a reason to think that God is impassible (can't feel emotions). (Zagzebski doesn't think impassibility and omnisubjectivity are compatible, and I agree. She does think immutability and timelessness are compatible with omnisubjectivity.) I can see that following immutability, one might arrive at impassibility. But I would say, yes, there is some element of God which is immutable, and another which is not, and figuring out the difference is important. I don't see a reason, at this time, to think that God is timeless.
Perhaps most salient for me right now is the question of Eternal Conscious Torment. Does God experience the torment of hell for all eternity? Zagzebski does not address this issue in this book, although she mentions that God may be able to timelessly apprehend a timely reality in one moment. I don't think this is really the same experience though. I think a timely experience is one which is experienced in time, and so omniscience requires being in time, such that ECT lasts forever for any omniscient God (if ECT exists).