I'm a sucker for "savage world"-type settings, so purchased this on a whim when it popped up. Review based on overall impressions after reading through; note that I haven't tried the game system or any of the publisher's other games.
Game system looks fairly streamlined. Skill-based with ability scores, on a d100 scale. There are no "classes", but characters can have "archetypes", which are Civilised, Barbarian, Nomad, or Primitive, and which determine starting skill point allocation. Alternatively, you can assign base skill points yourself and "roll your own". Checks involve rolling against your ability and skill scores with d100, and can be opposed.
The game world has all the standard Conan-type places and races (Cimmerians, Hyperboreans, Picts, Stygia, etc.) albeit set in an early version of "our" world map with areas corresponding to real countries. There is a bit of backstory about the rise and fall of the serpent men, the arrival of Lemurians from another world, and so on, as well as a small gazetteer; it's not particularly original or rich, but provides enough to provoke the imagination and weave stories in the setting. The magic mechanic cleverly represents it as, "things mankind was not meant to know" by ensuring characters slowly lose Empathy/Humanity points for spell casting, which is cool; there's a nice teaser list of spells ("Call Kraken" being my favourite...) and rituals and a separate listing for "true" magic, which is beyond the ability of humans (or should be). There is a list of monsters too, but no sample adventures.
Overall, the product looks pretty good. Text is occasionally clunky (mostly in the setting sections) but generally clear and readable. Art is in colour throughout, and is high quality, but some of it is clearly "stock art" and really doesn't fit the setting at all - there are pictures of elves, dwarves, etc. in standard "medieval fantasy" garb and poses, which is a little jarring. There are also just a few too many references to the publisher's "other system" ("Faeries Wear Boots!" yes! with that annoying exclamation point! all the time!) and some content about the faerie realm which again doesn't really "fit" and may have been lifted straight from the other product.
The biggest thing that keeps me from recommending this product outright is: Primeval Thule. If they are the same price point, I'd have a hard time recommending Beyond the Black Sea over that, simply because Thule is vastly more rich in terms of setting detail and "atmosphere" - this just feels a lot more sparse. However, if you're looking for a "savage world" game & setting all rolled into one, that is quick to learn and doesn't require a bunch of other sourcebooks or systems, or if you're a fan of classless/skill-based systems, it's worth giving Beyond the Black Sea a try.