A colleague arranged for 12 of us to go whitewater rafting one weekend, and we went with Pierose Swiftwater.
There are two sites they operate: Slim River, Perak, and Sungai Selangor in Kuala Kubu Bahru (KKB). We were initially scheduled to go to Slim River, but the morning of the trip, Pierose called us and directed us to KKB instead, as the water levels were better. Despite the last minute change, we were quite happy with the level of clear communication Pierose maintained with us throughout the morning.
Upon arrival at KKB, we found the crew all ready and waiting for us. We had a short breakfast at a nearby mamak, then was directed to the river site. There was a short briefing on the schedule for the day, then those drivers of cars who drove up to KKB were led to park their cars at the end point (where a jeep would then ferry them back to the river site) while the other participants made a half-km trek upriver for some basic practise on how to float with the life-jackets. It was great fun floating a ways down the river to the original start point!
Once the drivers had rejoined the group, we were given a safety briefing. Pierose was quite good at that, giving amusing instruction whilst still maintaining clarity & ensured everyone understood (almost all the participants that day were first timers). Briefings were conducted in English (very good command of it) and sometimes lapsed into Bahasa, but if you didn't get anything then all you had to do was ask.
The crew then pushed the rafts into the water and the groups were divided up fairly quickly. Two guides then got into each raft and off we went!
All in all, I was very happy with the experience, despite some nervousness and not knowing what to expect. The crew were very capable, knowledgeable and professional. Good sports, too! Spotters were stationed at key points of the rivers, and rescue for those flung overboard was fairly quick.
All in all, the excursion lasted about 4 hours: 1hr for gathering & briefing, 3hrs for the actual rafting. Pierose ended the trip with a delicious lunch for all participants, as well as showering facilities (at the KKB site, anyway).
Be sure to bring sunblock, a towel and dry change of clothes!