We were there last month. We loved it. The facilities were okay, hot showers are free. My kids loved it....scrambling through the creek, which was cold but clean. Digging for thundereggs was hard and hot work and the blisters have only just healed on my hands. There is a pool, a cafe, mini golf, horseriding and 'adventure park'. The paid activities are quite expensive, but we had a ball in the bush, creek and pool. There is also a small shop with basic supplies as well as cold drinks and iceblocks etc.
We didn't necessarily have the best campsite, we were right in the middle of everything. there are actually two different companies who have camp sites there. Thunderbird Park and then Mount Tamborine Caravan and Camping (or something like that). If you are going to stay with the Thunderbird Park mob (as we did) and want to be close to the creek I would suggest site numbers 628 or 629. After having a bit of a walk around the camp ground we decided they looked like the nicest sites. They were shady and right on the creek as well as being a bit away from everything. However they are also a bit away from the toilet...probably a 150 m walk.
There is the best lolly shop a short drive from the camp ground, at Curtis Falls and the new Tamborine Brewery is beautiful (there are other breweries there but it is definitely the best) with a great restaurant.
Have fun, I think you'll love it. We did.