This is a great app. I completely rely on it for my commute. It eve gives you real-time station departures and lets you know exactly how late a train is running.
Just be careful: if you have a transfer, make sure you go to settings and set the minimum transfer time (I use 7 minutes - if you use 2 minutes, for example, you only have 2 minutes from arrival of train 1 to departure of train 2 and you might miss your connection). This is particularly important if you travel out of Penn Station NYC to a Secaucus transfer.
LBINJ about NJ Rails