The lack of news and reviews for Grant Comes East has been striking. Here's the most I could scare up while Googling.
In giving what she thought was an endorsement, gossipy Liz Smith put her finger on the central problem of this counterfactual novel:
This is a very readable story of how President Abraham Lincoln finally put Grant in charge and changed the course of history.
Let me rephrase her sentence: in the novel, Lincoln put Grant in charge to get the same historical outcome.
That's not going to excite alternative history readers, as I pointed out here.