It concludes FMA, so if you havent, please see it! It's good!
And if you have, then Brotherhood is definitely your next step
I was doubtful too at first, so I read the manga. It was so good, and then I couldn't resist watching Brotherhood!
Brotherhood ends much happier. There are characters that are hard not to fall in love with. The humunculi are much easier to understand, too, and Edward's father plays a much bigger (and much less bone-chilling) role. I really do recommend it.