Spirit Tracks is a game with good ideas and concepts, but sometimes poorly executed due to its control scheme. There are several situations where you'll deal with the imprecise touch based controls, leading to a sluggish gameplay experience. That is greatly felt on
the Snow Temple, where you have to freeze the water with the boomerang several times , and on the Tower segments where you have to (very) slowly move one character at a time to the places you need to be and also on some moments that you're required to blow on your mic to play the flute
That said, everything else on this game is on point, the level design is nice, the character design is well made and well thought out, even the Realm transitions are very neat, the soundtrack is amazing and there are cool details like the overworld song synching to the train sounds. The game's world is alive and diverse, with events happening in parallel with the player's actions, characters going on and about and even some out of the way unique stations with minigames and mini dungeons with rewards
The story is good, the "twist" of having Zelda actually helping out and playing a bigger role on things is an interesting and needed touch for the franchise
The train driving, which is the main mechanic, is well toned. It isn't too complex nor too simplistic, casual/Zelda players will get to enjoy it as much as
Densha de Go! [電車でGO!] fans (those will feel very familiar with obeying the speed limit and whistle signs while having passengers). The side and fetch quests of this game are the most fun I've ever played on a Zelda game, I loved spending time taking people to places they needed/wanted to be and delivering goods by train
It is overall a neat experience, although frustrating on some specific parts, that would perform better as a main console game