Like almost everything in Cambodia the good and bad of this ride were in stark contrast to each other. I booked the 8 am - 5 pm bus from Siem Reap. And had another bus to transfer to in Bangkok around 7:30 pm. There was no 8 am bus. I was told it was due to AC but think it was actually due to lack of passengers. Lesson 1 - plan on the bus leaving at 9 or just book for the 9 bus. Once on the bus things were pleasant. Comfortable enough seats and the attendant was very kind and friendly.
After a couple hours you arrive at the border crossing. This was enough to convince me that flying would have been the best option, despite cost. It took close to 3 hrs, which the attendant said is very standard. Nattakan does get you very close to the Cambodian immigration building so you don’t have to guess where it is. Petty quick on Cambodian side. Then in a line for 2.5 hours on Thailand side. Very slow moving, jam packed, hot small room. If you haven’t budgeted enough transfer time this wait can be agonizing. And even if you have, it’s a long time to stand more or less still. Lesson 2 - when it comes to Cambodia or border crossings, fly. Once on the other side the driver was there looking for us. We waited for awhile after all but one of our passengers had made it through. But then ended up leaving. Some nationalities do not get through easily at this border crossings.
The rest of the drive was pleasant, lots of slow going traffic once we were an hour or so outside Bangkok. The bus finally arrives to the station close to 8 pm. Lesson 3 - a minimum of 11 hrs should be budgeted for this journey. Missed my transfer bus. The Bangkok bus station is huge and primarily used by Thai people. No English counters.
We were provided a snack when boarding and a hot lunch, to go type entree after the border. Would take again with more time.