This is an excellent product line for those interested in RPGs in the romantic fantasy (RF) genre. It's also purposely limited to the three core books so it's not a never ending avenue of expenditure. Which, IMO, is a great thing. (It does have some freebies, extras, and a forum at the greenronin site.)
I agree with earlier reviews but wanted to add a sort of meta-review (of this, the Companion, & Worldbook) and hopeful "idea pot" inspired on suggestions in the Worldbook.
The system itself is heroically based with powers being a more balanced, and therefore sometimes limited. (If you're not into/knowledgeable about RF, think of a fantasy version of Star Wars and "The Force" -including all the negatives for doing evil stuff- and you're 90% there.)
Because of this, if you have a mixed group (like us - some RF fans, others just casual D&Ders), and some GM's styles aren't strictly RF, the BR system & setting is still really ideal if you switch off GMs.
For example, the way the warrior role/paths (paths are suggestions and ideas for roles [D&D classes]) progress in BR it gains in virtual toughness, which means that you can have some really fun swashbuckling type adventures which still doesn't have to "break it" for the RF fans.
The World, and especially Worldbook, seems to have instinctively felt this would be a good merger since there's lots of coastline and a very good description of a island nation which just begs to be expanded upon. (There's also a swashbuckler in the Companion.)
Mix that with a more "Pirates of the Caribbean" type Freeport (another Green Ronin product line) with the currently free True20 intro adventure and you've go a lot to run with. (True 20 & BR are very compatible - sort of like D&D 3.0 & 3.5.) Take it to Mindshadows (a sort of fantastical Indian subcontinent inspired setting), 7th Sea inspired (fantastical Europe), or Al-Qadim/Tales of the Caliphate Nights (1001 nights inspired) and the possibilities are endless.
Make sure the PCs have a ship in good order and a good Wind Shaper (someone who controls winds) and the party can be back in time for the RF GM to take over during GM switch week. :)
On the bad side, doing this sort of mixed adventure will take some work. And strictly speaking there aren't any sailor/pirate paths listed. But there is a small section in the Worldbook with a sample pirate leader.
And if you just MUST be dark about it all, BR really allows for that too. Just take inspiration from Midnight (a game line inspired by the idea of a Sauron-type being winning the war of middle earth) and make the evil nation of Kern much more powerful, Jarzon (a nation of extremists) much more rampant, and the plains of Rezea besieged, alienated, and unwilling to ask for help from treacherous outsiders and it could be enough to make an anti-hero such as Elric smile in evil joy.
Having said all that, here's a quick lowdown system-wise: BR is offshoot of the d20 (D&D) explosion but has some differences. These include abilities being -5 to +5 which is both the stat & the modifier, which is nice. Characters don't have hit points, they have a static damage track. This makes if have much more in common with games such as BRP (RQ, Stormbringer, etc) then d20 since combat can be pretty dangerous. To offset that danger, there's "Conviction" which more or less acts like "Fate Points" in other games. Plus for certain characters toughness goes up which helps stave off such damage.
BR exclusively uses a d20, which makes things easy.
As stated earlier, there is a pagelist worth of magic powers (arcana) that cover a good degree of the standards of fantasy games. There are extra powers in the Companion, and they are all divided into different types (such as psychic, shaping, and animism, to name a few) that help players and GMs follow certain character types. (Ultimately, however, you can mix and match at will.) Arcana use is limited by the user ultimately suffering physical exhaustion. If you use powers that are "anti-social" (dominating people, etc) characters can suffer from corruption which could finalize in NPC-ville.
Feats are there, and skills, a bestiary, and a d20 conversion section (But that will take some kibitzing). Background, GM suggestions, and a bestiary round out the book.
As an aside, wealth is handled by a wealth rating vs actual money, which stops accounting, but can be weird getting used to.
The Companion is nice because it includes a nice expansion of paths, which really helps give the GM a framework for characters in the game, skills, arcana, a bestiary, and general concerns in the game.
The Worldbook expands on the background given in the main rulebook nicely. Without offering spoilers, it adds several juicy bits and location descriptions for adventure & campaign ideas. There's also maps, an adventure, and adventure seeds.
As stated elsewhere, if you're looking for more there's always True20 material that can be kibitzed.
Rated a 5. for how great it is & 4 for micro-world GMs like me since they really should have more sailer/pirate rules/paths.