I've just entered Cambodia from Thai land crossing the border at Chong Chom/O'Smach and there was absolutely no problem with the crossing. I have Australian plates and a BMW (GS) so I was more of a spectacle than anything else to the Thais as they rarely see bike of this size in the area. The Cambodians didn't even care. They never asked to see papers, rego, or anything, just a passport and valid visa. The road south of O'Smach was pretty poor, it is littered with potholes and is dirt for the entire ride to the main Sisophan-Siem Reap highway (also dirt for 33kms to Siem Reap). The going is slow, about 40-60kms/hr at best but it is scenic and I didn't care that the 130km ride to Siem Reap would take all day. The small villages on the way are well worth spending some time in as there are many photo ops and the food is great. After Siem Reap I'll be touring Cambodia and then trying to get into Vietnam... if that fails then it'll be off to Laos.