I don't usually write full reviews, but I think I might start. Probably less for series, more for movies; triggered by seeing both a really great movie and a terrible one in the same week.
I'll start with the bad, Fullmetal Alchemist: The Sacred Star of Milos. I had seen both series and the first movie and assumed it would keep up the same quality of art and storytelling I've gotten used to seeing from this title. It failed to live up to those expectations and then some.
The art is bad; I'm not going to sugarcoat this. This is BONES we're talking about, a studio that's well known and respected and certainly had the money to do better. I haven't seen lines this sloppy in a long time, and certainly not ever from a theatrical movie. They are thick, chunky, and wobbly; a style that might have worked for something a little more artsy, but really pulled me out of the movie as something that just did not fit.
I made the mistake of watching this in 1080p, so it may not look so garishly bad in SD, but this was on movie screens; I'd expect it to look better than bottom of the barrel TV anime.
The story is about what you would expect from a movie addition to a series; and by that I mean, bad. It's forced, boring, and has no character development aside from the characters they threw in there to make a story in the first place. So basically, this is no better than the -insert generic shounen anime here- movies.
I would have cut it some slack since they're trying to add on to a series that already had its conclusion, however, even within the movie itself there were major plotholes and contradictions that just didn't make any sense.
In conclusion, bad art, bad writing, the animation and music was...okay? It failed to get any emotional response out of me other than boredom. I don't recommend anybody see this, even FullMetal fans will only be disappointed.