An enjoyable journey
The train runs between Greymouth(departure: 2PM) and Christchurch(departure 8AM) covering the distance of ~225 kms in ~5 hours. You do get to see some great scenery as the train passes through Southern Alps, valleys of the Waimakariri river and Canterbury plains. Rated as one of top railway journeys in the world, the train has a pantry car and an open carriage from where you can click pictures.
Clear weather is critical to enjoying passing scenery
But if the train is delayed or the weather is not clear, you are unlikely to see anything worthwhile and then suddenly, the tickets appear to be expensive! Luckily, the day I travelled, the weather was clear.
Discounted tickets not available to all
Now for something very interesting. Discounted train tickets are available only if you book online from a New Zealand IP address. These tickets can be over 40% cheaper but are non refundable. Normal fares are ~NZ$200 -220 per person while discounted tickets can be had for ~NZ$120 and more. However, I understand that booking over phone from anywhere in the world will entitle you to discounted fares if available. I booked my tickets online after arriving in New Zealand, about 10 days prior to the scheduled train journey and still managed to get discounted fares.
View from TranzAlpine train 
View from TranzAlpine train
