What does it bring over open ttd?
Personally, it was not my cup of tea in 2004 and I always stuck to the original (which I think was/is the popular opinion of the game) and I in particular dislike the complexity of RCT and Locomotion's construction UI compared to TT. But I do think Locomotion has some charm and perhaps is best viewed not as a sequel, but a different take on what TT could have been.