Ummmm...well, Rain is a kind of manga with that cliche kind of story really.A love story between a young princess and yep u guessed it, the strongest knight of the kingdom 'Rain'.
Even though the story is predictible however the art is awesome and the characters are very likeable. The battle sequences are very good as well but for me the heart and soul of this manga is basically Rain. His strenght, laid back back personality and sometimes his over the top antics give this manga a life.
So overall I would say it is a good read definately worth your time if you like the classic type of love story.