I just finished this show on Amazon Prime. I generally liked it, but felt like it went down the fantastical road a bit much, especially with that season 2 finale. I do agree with others that is borrowed heavily from The X-Files (my favorite TV of ALL time!!!) but failed to learn from it. The X-Files gave you just enough juiciness to lure you to the next episode. Blue Book knocked you over the head with all the UFO sittings and stuff only to debunk them a majority of time. It kind of lost it's believability, seeing as it is based on real stories and J. Allen Hynek's revolutionary work.
Still, I would like to see the series continue, too bad it was canceled.
Yeah the sub thing kind of went down the scifi road. I think the History Channel blew it with all the new UFO stuff coming out and the Pentagon releasing more info in June. It would have tied right into that stuff and the promos would have written themselves!