We did treks 2 and 3, since trek 1 wasn't available. Our tour guide was great and lovely, however the treks themselves weren't too special. Despite seeing some slightly cool sites such as a cave and a waterfall, we weren't able to go into the cave. We also didn't see much scenery (admittedly I was warned of that before going on the tour). In other words, the treks we did were a little underwhelming.
Additionally, our driver ran over someone's dog on a main road and kept on driving. The poor dog yelled out and his dog companion checked to see if it was ok. The driver didn't stop or care at all. The driver pulled over after I asked him to and I told him what he'd done. He responded with 'i didn't see it until it was too late'. I don't believe this is true, since the road was wide, sunlit and the dog seemed very visible. There was also no indication of him slowing down when approaching the dog. (It was safe for him to slow down).
I asked if we could turn around and see if it was ok, however he said no 'we have to get back to pai'. The driver didn't care at all about the animal's welfare or my feelings. I told the reception about the incident, and he drove off quickly after saying that he hit the dog. One of the receptionists cared, the woman receptionist didn't seem to care.
Overall, the experience was ok but slightly underwhelming, poor organising by the company, and very disappointing attitudes of some of the staff (mainly the driver). If you do this trek I'd advise including trek 1 on the itinerary, since it has scenery included.