For any FMA fan, this box set makes the most sense economically. Of course, it's annoying that most fans would likely have purchased a few books from the series already before finding the box set and so will have repeats of volumes. I had the first nine volumes already and now I want to sell them, which might be hard to do.
The poster is rather small and not particularly impressive. The extra book is designed for a young reading audience but is still nice for a fan to read. I have been storing the box upright and the velcros holding the side flap closed have stopped sticking (though it's not like the books will fall out even without the velcro).
I don't know anything about the translation history for FMA, but I think there must have been a second release of some of the first volumes. I remember reading, for example, that in volume 8 page 66, the original Japanese panel was changed from a cross to a stone slab to avoid offending a Christian North American population. But in this version, it wasn't changed, which makes me think a second release was done at some point. The box set would then appear to contain the most recent release. I've noticed a few typos in translations and some inconsistencies in name spellings for people and places. "Kimblee" is once spelled "Kimbly", for example.
Despite what I've noted, I am incredibly happy with this purchase. To anyone who became interested in FMA through the anime FMA: Brotherhood, I recommend buying this. The original manga story really fleshes out and adds to what we see in Brotherhood. In particular, Brotherhood edited out a lot of the humour from the manga.