Overall, I gave Gyrfalcon 3 stars and feel mostly positive about it, however for a while there it was looking a bit uncertain since the pacing of the first half of the book leaves a little to be desired and it's very clearly the start of a series (with all the additional world-building that involves).
The basic premise is that what's left of humanity is fighting a mostly-losing war against aliens and our main protagonist is a special forces type with serious daddy issues, not the greatest start for a character in my opinion. We first meet Bennett in the context of his team before he's shipped off (sorry, that pun was accidental) on his own to a mission using the eponymous warship commanded by his estranged father as a means of transport. They argued about Bennett's career path and also about the surprise discovery of his sexuality, after said father walked in on Bennett and a much older man.
Bennett has time onboard the Gyrfalcon not only to start to rescue his relationship with his father but also to get involved sexually with one of the other pilots. Some people might struggle with this aspect of the plot, since it's clear Bennett is still in a serious relationship with the man with whom his dad found him all those years ago; since they're apart a lot, they've agreed to an 'open' relationship and both have taken advantage of this in the past. I'm not sure quite how I feel about it myself, it feels more than a little hypocritical of Bennett to have the attitude he does about Joss getting laid while he's away and yet enthusiastically embrace this opportunity for himself (repeatedly).
As a result, that whole part of the relationship could be the make or break aspect for me when it comes to reading the rest of the series, though I may well see how the next book (Heart Scarab) handles it and go on from there. Likewise some of the writing is a little clunky, as there are a number of times where we get the same scenes from both main characters' point of view, which seems a little unnecessary.