I watched this on Netflix the other day. I've tried to avoid blatant spoilers, but the following might give away some aspects of of the plot.
Wiki describes this as a "military science fiction thriller action film." IMBd says:
>>>Civil Unrest in the European country of Moldova has US forces engaging the insurgents however there is a new threat who has decided both are their enemy. This new threat resides in an alternative spectrum that makes them invisible to the naked eye and instant death to anyone confronting them. Locals believe they are Spirits of War but others believe they are superior arms technology fabricated by the Moldova government.<<<
I wanted to like it because the trailer reminded me a little of Edge of Tomorrow, which is one of my favorite movies. Unfortunately, Spectral is not nearly as good (in my opinion).
Without getting into spoilers, the acting is okay, the plot is not too terrible, and the special effects are also not too terrible. And, thankfully, the movie doesn't include a contrived romance thrown into the mix in an effort to make it palatable to female viewers.
I can't quite put a finger on it, but overall the movie never pulled me in and made me forget I was watching a movie. The characters were a bit too cliched, and the plot started to get somewhat predictable. This might not bother others, but the "explanation" of what was going on about half way into the movie seemed hokey to me. Pure fiction (e.g. The Matrix, Donnie Darko) doesn't bother me, but contrived quasi-real world science is annoying.
Overall I'd give it a 6 out of 10. If you really like this genre, it's probably worth watching.