The game's main draw lies in its fun and fast battle system. Once you get in touch with one of the frozen spirits the game switches to a battle arena where you engage your enemies. You can either attack them directly with your stick, or use one of your four skills; Ring, Line, Wall and Slow. It all depends on how far the enemy and you are from each other and where you're facing. It's pretty fun to burn your enemies to a crisp, but beating them with a stick can also be pretty stress-reducing.
Graphics-wise the game is first rate. Unlike msot of Ocean's other games it uses mostly rips, but Rubi and some of the monsters and NPCs are self-made, just in the style of Secret of Mana and Seiken Densetsu 3, like the rest of the game. It's very consistent and nice to look at, with lush green scenery and relaxing beach areas. Rubi and her enemies are pretty well animated too, especially if you consider the short amount of time the game was created in.
The music, also unlike Ocean's other games, is public domain this time, but it's still nothing short of greatness. It always fits and is also pretty consistent. The sound effects are also just fine, nothing to write home about.
So, if you have one or two hours to spare Rubi is the game for you to play! Just don't expect another Star Ocean in terms of gameplay and you'll find it to be a thoroughly enjoyable experience.