One of the worst experiences ever.
The fact train was late for departure with 20 minutes was not a big deal.
Then, the train conductor seated us in some other empty berths, because he was sleeping in out berth.
We had 2 berths, one lower and one above, but we only used the lower one since we both had space there.
The bert is the most uncomfortable beth I have ever travelled (my experience consists of european berths: greek, turkisch, romanian, hungarian, polish, german and french). I am 1,83 height and I could just fit.
The wagon is not very comfortable as the whole ride seemed a little bumpy. We couldn't sleep at all the entire night. THe curtains of the berth are not so good for privacy and also the wagon is very noisy since there people not in the mood to sleep.
The toilets are very dirty (one thai style - squat and one western) and smelly.
There were also cockroaches on the aisle.
In the morning there was an employee asking if we want tee of coffee and assuming it was free I asked for 2 teas - big mistake! We had to pay 160 THB for them. I find this outrageous since we paid a lot of money.
Prior to this train we took a train from Bangkok to Hua Hin (2nd class with A/C) where they also provided us a meal and free drinks (water and tee) - train that just cost us 828 THB.
The only positive things would be the sunrise in the morning and the fact you can bring more baggages.