I like that the captain has a healthy dose of scepticism about Icheb. Unwarranted of course! But in her position she has to be careful if not outright dubious.
The new mystery is quite unsettling. The Borg could be back [I like the idea that they were not completely destroyed by Janeway's endgame] but worse still they've encountered someone or something that can take them on.
Added to that, I think it is safe to safe having a former drone as your commanding officer and being told in stark tones by said commanding officer that the Borg adapt has to be pretty unsettling - no check that- freaking out time unsettling.
Good things. Liking the build up with the character introspection form the captain adding depth to her and reassuring the reader that she is probably suited to this mission afterall. Yet also the fact that she recognises that Starfleet would sooner likely change her billet than Icheb's is revealing too.
Nice development and yet the story has a frantic pace keeping the story zipping along.
Looking forward to more.