You have to admit it- steampunk is pretty damn cool. FMA isn't the full-on goggles and Victoriana style- the aesthetic is more 1920s/30s, for one- but it uses both the styles and the theme of the time really well (struggles between dictatorship and democracy, anyone?). Plus, there are badass mechanical limbs all over the place! 9. The artwork
Hiromu Arakawa's character designs are not the most complex or realistic but with a huge cast (even if you only count the characters with names) no two are alike, and their apparently simple faces express the whole gamut of emotions and personality. She (and her assistants) are no slouches with the backgrounds either- from rural villages to mining towns to mountain fortresses, in houses, hotels, shops and shooting ranges, every bit of scenery is evocative and distinct. This also leads to... 8. Attention to detail
One of the best things about FMA is that every time I re-read bits, I notice something more. For example, a brief shot of Roy in bed chapters after he's severely injured? There's a little bag of medicines on the side table; hardly even visible but they're there. This also goes for all the detail in her research, from the Hebrew names of God on Ed's Door of Truth to the fact that every single weapon you see has a real-life, early 20th century analogue. Then there's the piles of research on medieval alchemy itself, on biology and chemistry, on war and the psychology of veterans... this is the kind of series where you can tell that the background research was a real labour of love. 7. The sense of humour
I realise this might not be a draw for some people, but I have a pretty dark sense of humour, and so, apparently, does Arakawa. There is no tragic, heartwrenching moment that cannot also be made fun of, even if it's only in the gag comics at the end. But when it does appear in the main storyline it still makes plenty of sense that a bunch of almost uniformly traumatised main characters would turn to black humour to live with it all. 6. The scary bits
I am not a huge fan of it as a genre, but I do enjoy horror employed well as part of a larger story, and FMA can be absolutely creeptastic at times. I get the shivers every time I re-read the chapter which reveals the identity of the final homunculus, or when the gold-toothed doctor shows up for the final time, or a whole bunch of other things I can't bear to spoil anyone for. The sense of menace and threat at the scariest times for the characters is conveyed superbly 5. The female cast
The majority of the cast are male, yep, and I won't pretend that I didn't wish there were more and better interactions between the women of the cast, but they are truly a fabulous bunch, from Winry and Pinako Rockbell, surgeons and engineers, to Izumi Curtis, butcher's wife and genius alchemist in her spare time, to Mei Chan, world traveller and medic at the age of about ten, to Major General Olivier Armstrong, border-defending general and terror of the military, to... 4. Lieutenant Riza Hawkeye
She gets to be a reason all on her own. Hawkeye is fucking awesome. That is all. 3. The mytharc
This, Mr Carter, is how to run a series for nine years and have the plot as tight at the end as it was at the very beginning. Arakawa had the main plot set out well in advance and it really shows- events link in to one another over years' worth of chapters, little references crop up again and again, and the plot is extremely well-paced in how events escalate and more and more of the Evil Plan is revealed. 2. The characters
I made special mention of the women, but every single character in the series makes it worth your time, from Our Heroes Edward & Alphonse Elric all the way down to characters with a fairly small narrative presence like Rebecca Catalina or Sig Curtis. Anyone who gets more than the odd scrap of dialogue has a distinct personality, and no character is reduced to a cliche or a single dimension. There are characters who I love to hate but none at all who I would rather just weren't there- everyone is clearly necessary and valuable to the story. 1. The themes
FMA is something of a perfect storm in hitting pretty much every fiction-loving button I possess, so I am biased here. But characters striving for redemption, trying to take their own terrible mistakes and make something better in recompense, characters with a sense of justice stronger than their own personal desires, a hugely disparate group of people coming together against a terrible evil, combining their skills and overcoming their enmities, the presence of hope in the most surprising places... I feel uplifted and inspired by this story, by these characters, and there's not much more you can ask than that.
Anyway, I really, really love this series, and I hope I've encouraged at least somebody to give it a go. It is worth every second of your time.