How well build is the train network in your country? Do you use it regularly? Why or why not?
Personally I travel by train a lot and just couldn't do a lot of stuff if I could go by train. For example I recently moved for university and I would have a huge problem visiting my hometown if not by train.
Sadly, no. Trains in the US are generally not a viable form of transportation except for local travel in a few large cities.
A few years ago I made a three hour trip by train. The arrangements were inconvenient, the travel was slow, the facilities were in poor condition, and it was relatively expensive. I would not do that again unless most of those things change.
UK here, not in a city. There are no stations near where I live and no stations near places I want to go. The least distant stations from me all have lines that run exactly perpendicular to anywhere I would want to visit. So trains are a complete waste of space for me and due to poor road layouts and too much traffic, and the extremely annoying habit of oncoming traffic to be completely absent where I can't overtake and densely packed where I otherwise could have, I get on my motorbike wherever possible.
Trains make perfect sense in London; if I lived there I'd be on the Tube every day, and I use it when I visit.