I love the tingle tuner too.
I think it really changes the style of gameplay though, at least it does for me.
Without it, just normally playing, it feels like a regular zelda game.
But when I use it with another person, the way I play is just totally different. It feels like more of a 'find something on Tingle Tuner, tell GCN player to go there...etc...'
More like I'm ordering him around on a mission or something.
i really like how it works, for me at least, it adds a lot of more replay value, and a different style of playing the game.