I've been a big fan of oriental rpg settings for years. I had the 1e Oriental Adventures, and multiple versions of Legends of the Five Rings. Ruins & Ronin is a new game based upon the S&W WhiteBox ruleset(which R&R is compatible with). While no setting is provided, it references Japan quite a bit, and the classes are designed for that style of game.
The book has a great Pete Mullen cover. Unfortunately, that is the only artwork in the entire book. I really wish at least some of the monsters and the equipment had pictures provided.
There are three classes in the game: Bujin (fighters), Shugenja (magic-users), and Sohei (clerics). People who have played Oriental Adventures should recognize the names. The system is extremely rules-lite, similar to WhiteBox. If you are familiar with any of the older versions of D&D, you should pick up gameplay in a matter of minutes.
The spell selection is straight out of WhiteBox. Nothing new here that I noticed.
The monsters are a weird mix of standard WhiteBox monsters and oriental monsters. I think a number of them could have been eliminated (slimes, oozes, normal ogres and goblins).
There are a number of really cool oriental magic items included, which is great for adding flavor. The equipment and weapons section also was completely samurai-friendly.
There is no honor system in this game, which I was surprised by. It is a feature element of the other oriental games I've been in. This may be a plus, though, as it frees up characters to be more free-wheeling ronin than clan samurai.
Overall, I like the game. It could definitely use some more art, and I think the spells and monster selections could be tweaked a bit, but it is a great buy if you want to run a chanbara-style samurai story.