A save game feature would be useful to have IMHO just so you don't have to start from scratch each time you play the game, that being said I really enjoyed the game and can't wait to see what's in store.
I don't know which version you have played, but in my I can't reset the progress. I can't start over :( . So once you are playing it gets you a bit bored after a while. And when you have plenty of money and upgraded train, you definitely wants a reset ;) .
The game is ok. I liked it. But it is rather for a quarter or two, not for a 3 hours of game. Short break plus some piano (Chopin?) music is quite relaxing :).