Bring hearing protection. If you forget, there are ear plugs at the front desk. Use them. USE THEM. You've signed away your right to sue them or participate in a class action law suit so if you lose your hearing, you'll just be wishing you used protection. It's like standing next to a fire truck for 45 minutes. Your ears will hurt.
That said, the workout is effective. I've never sweat so much in a class. You clip into your bike that's adjusted to your height and you're all in for the next 45 minutes. The instructor pushes you to go as hard as you can. It's a full body workout. There are weights for the upper body workout portion and your abs get a good workout too.
I can see why they have a cultish reputation. You ride in sync with everyone else in the room to the pulse of the music and there are candles that 4 lucky riders get to blow out.
Great workout but terrible for your ears and wallet.
The facilities are beautiful. The bathrooms feel like you're at a spa - anything you need: face wash, different moisturizers, hair ties - anything at all - it's there. The lockers have USB chargers for your phone.
There's also free smart water and a towel waiting for you on your bike. You might want two waters.