I've had 2 births, both with HypnoBabies homestudy.
It is enough, and I recommend highly against other classes, particularly Bradley.
The program is designed to be a stand alone program, even the homestudy. In fact the program recommends strongly that you don't attend other birth classes. The idea is that HB is a full program, you learn the basics of pregnancy, nutrition, signs of labor, stages of labor, typical interventions, post partum issues etc. It is, in my opinion a full course. They recommend staying away from other birthing classes, particularly the hospital based classes because HB uses a specific vocabulary and imagery meant to teach you to have a calm and relaxed (but aware and educated) birth, and having been through my hospital class and been through the Bradley book, and a great number of other natural child birth sources, I agree the constant discussion in Bradley in particular that pain is necessary and important part of birth is completely contradictory to the HB methodology. If you are planning on birthing in a hospital or birth center, I recommend going for a tour, it was very helpful to be able to visualize the place and helped during my birthing time to know where I was going and have some knowledge of the place.
Your partners participation is actually very easy, very little for partner to do, they need to use the vocab and learn two specific cues, nothing intense, nothing like specific pressure techniques. There is a cheat sheet in the book that I had DH read and I talked with him a couple of times about what I would need from him.
All of that said, if you can honestly believe and give your mind and heart over to the use of hypnosis and HB, it's quite easy to filter out the scary, negative crap from other classes. But you have to actively be able to push aside that crap, forget that crap and believe that HB will work for you. yeah I know that some women experience pain during childbirth, but honestly believe that I don't. I didn't feel pain, didn't scream and yell at DH.HB works, it isn't that hard, really doesn't take a lot of effort and really really doesn't require a lot from your partner.