This was fun! It took me a bit to really get interested, there was a bit too much info dumping here and there, I don't really need ALL the details about military formations and weapons and whatnot.
I thought Dex was totally different at the beginning than how he was once he joined THIRDS, but I guess that made sense, since his life was kind of a mess in the beginning. He also acted younger than 33, I wouldn't have pegged him over 23-24. He was totally adorable though, cute and funny and sarcastic as hell.
Sloane was great too, all gruff and tough and wounded warrior. I also figured out who the bad guy was pretty early on, so maybe the mystery aspect could use some work.