Don't do it for the comfort but for the experience. The train itself isn't too comfortable to sleep ok but facilities are all fine and everything ran on time. Quite the experience but don'r expect a great night of sleep!
It doesn't make any sense to offer this intenary as a two day trip. I essentially attended two different one-day tours. The first one ends at 4pm, then they drop you at the guesthouse without any recommendations about what to do. The second day the tour was supposed to start at 11, but I was sitting around waiting for the pickup unil 1pm and we finished again around 4pm. It's an very touristy tour. The guides were hard to understand (but that holds true for most tours in Vietnam...). The communication over whatsapp was good. I recommend spending a few dollars more to do an adventure tour with camping in the national park.
it was a pleasant experience. the bed was clean, soft enough for this kind of bed and no bad smells from the toilet. a curtain for more privacy would be good if your neighbors are not that pleasant.
The train was OK. It arrived perfectly on time which was great, but sadly our carriage was the only one where the air conditioning wasn't working, so it was a very long, hot journey to Dong Hoi. We arrived around 15 minutes late, which was OK, all things considered. The beds were reasonably comfortable, the cabin was clean and the views were pretty amazing. The toilets are very unclean, but again, we could deal with it. Overall it was about what we expected.
We booked a private (2 person) cabin online. It was available to book and did the payment etc. only to hear a day later that this cabin actually wasn't available. It was a lot of money already paid. Then the contact center told us we could book a 4-person cabin for the two of us for an additional +/- €50 (ehm, excuse me!? We need to pay extra for your mistake? And not a small amount either.. ). We decided not to do this and to just share the cabin with two others. We left from Ninh Binh but our tickets had the departure time from Hanoi on it, so this was not correct either. On the night itself we entered the train, the toilet(s) were disgusting and the staff was smoking inside the train. The cabin was fine - clean and quite new. There were two other beds which were reserved but not occupied yet. After a while the cabin attendent/conductor came by to check our tickets. He closed the door and told us we could have the whole cabin for ourselves for +/- €25 extra, we had to pay him in cash and he would make sure nobody came in... It was all very strange and dodgy since there were welcome papers with guest names on the other two beds, but perhaps those people cancelled or missed their train. Since we really wanted the cabin for ourselves we decided to pay him the amount. However, I believe we would have had the cabin to ourselves anyway, and this cabin attendent just wanted to make money. He took advantage of the situation since we were so tired (it was the middle of the night). The cabin and train were fine, but we felt like we were scammed by this cabin attendent which left us with an uneasy feeling, and the booking process with 12 Go Asia was such a hassle as well. I would appreciate a compensation and would also recommend others to book directly at the train station and not with a partner online.