This is an excellent and charming little game. The art's uniformly great and the rules hang together well. It's a simple game, best suited for beginning players or groups who're interested in something lighter. I usually run much "darker" or at least more serious games and Ryuutama offers a charming alternative. I ran it over the course of two sessions with five players (all of them experienced in RPGs) and I will say that with that the "balance" seems to break down in the travel minigame. With enough characters there are a good number of combos to mitigate most failures. The enemy types provided in the base game also don't provide much of a challenge to that many characters, unless you throw in quite a few of them. This wasn't a huge problem for me--combat's not really the point of the game, nor is grueling travel always desirable. But the occasional dash of peril is still important, even to a gentle game like this. Sticking with three player characters might be the best strategy, until you have a hang of the system and can tailor the challenge level.
Again, I really recommend it despite my minor nitpicks (which aren't even really nitpicks, just areas that the game doesn't intend to cover). Ryuutama facilitates player creativity and buy-in as the GM and players collaboratively build destinations, it puts the focus on developing nice and fun relationships between characters (PCs and NPCs), and it plays very quickly and intuitively.