Just look online at the google reviews.
I've been several times but just can't remember who we used of the top of my head. Every time we went we had a great time.
Strongly recommend doing a full day. Just about the time you think you want a break, you'll stop a and they'll cook you lunch and take an hour or so break. Then you're ready to go again. Each time lunch was good hot food (like pasta, fajitas, etc.).
Bring appropriate clothing. We just wore old tennis shoes, swimsuit and I had a heavy long sleeve dry fit to keep warm. Felt like renting a wetsuit would have been over kill. Wife wore a 1-piece but had capris work out dry fit pants and a log sleeved dry fit on top. Water is pretty cold (although not as cold in Aug as it was in May). I brought a pair of cheapish sport sunglasses with a lanyard so I would not lose them (or if I did was not worried about the $$).
Bring some extra cash and tip your guide. The three times we went (years apart each time) the guides we had were great and made sure we all had a good time. There were 6 of us so we had a boat to ourselves which was nice. Me, the wife and 4 boys all worked great together navigating the river and following instructions so the guide took some more adventurous routes.
Honestly I thought they stopped by now b/c the water levels are so low, but maybe not.
FTR, My wife hates roller coasters, adventure stuff but she absolutely loved the white water rafting.