I like it. It has a nice flavor. But I think they are quite powerful. I have not analyzed them, but I came across some things I remember.
Recruitable fear-causing troops. Say 5 of these guys can rout 1000 militias. Size doesn't matter when faced with fear. Rout checs are not dependent on losses, so the squad will be subject to rout checks regardless of losses (with a bonus due to squad size, but in the case of militia it might not help). Thus only highly magical units has fear. The nightmares of the onyx amazons are the only recruitable ones i know of, and they have 20 enc to compensate.
Hoplite shields. Parry 8 is high (I was about to write insane, but that sounded a bit offensive
). A towertshield is pary 6, and is supposed to be the largest shield in use. I doubt few magical shields has parry 8. With parry 8 no missiles will ever hit the unit.
The Hoplite shield bash is also quite powerful. Second bonus attacks are good. I think the bash might come from another mod, but it is still powerful.
Gilgans can get 5 in blood magic (6 if 10% lucky). This is higher than all MA nations, with the exception of R'lyeh IIRC. This might not be a problem, but you should consider if you want them to be: 'A race of bloodmages of unequalled powers. No other nation have so immersed themselves in bloodmagic as the Gilgans. Their skills in bloodmagic is legendary and can almost rival the powers of the gods.' Something like that
As I said it is not a problem in it self (especially since blood magic don't benefit as much from increased skill levels as other paths), but you should be aware that you are making the most powerful blood nation there is.
I didn't play the nation, just checked around, so I cannot say if they are unbalanced on a grander scale. Low MR etc might well compensate for other strengths. THe two things I would be concerned about is the fear and the hoplite shields. The Gilgans go nice with the flavour of the nation, even though they are more powerful than other MA mages.