My first reaction to Betrayal

Here's a break in all things Kyp. Betrayal has NO Kyp, which is a bit hard to swallow, but I think he will show up in the other books. I think there is still unresolved relationship between the GA and the Jedi. So far the new book ties into the previous books only by allowing that Jaina and Zekk continue to work together (but are only hinted at romantically), and that Jacen continues his Sithly behavior. Nothing else from the other series is really dealved into.

So where do we go now?

Jacen Solo is a Sith.

I mean he’s only a little more a Sith than he was in Dark Nest. In those books he lied continuously to get what he needed, he believed the ends justified the means, he once stated power unused is power wasted (which was thought by Darth Maul in some book). Yes, Jacen attacked T’aa Chume, but she was evil and tried to kill his daughter. That act of revenge could be somewhat justified by a modern Jedi. Jacen mind wiped Ben also. Lastly Jacen agreed and admired Anakin Skywalker after his Darkside turn! So one might say Jacen was already a Sith.
In Betrayal Jacen acts the same way, but by the end he openly accepts Lumiya’s tutoring and he kills Nelani in cold blood. So at the end of Betrayal there is nothing to doubt or debate: Jacen Solo is a Sith! And that is way more cooler than being some Darkside dabbler.