So I just read Harbinger. I'm planning to share my thoughts on the series in this thread.
First impression is that this book definitely owes a lot to NuBSG, even though the stationary setting will invariably liken DS9 comparisons. Harbinger is grittier than anything we've ever seen in TOS, and there is even a Boomer analog.
I like the humor, especially the bit with the poor Tellarite. I also liked the twist in the middle, definitely unexpected.