I think it very much depends on you and your circumstances. I had the same questions when I was pregnant, and I decided to do NCT and then just buy the hypnobirthing CD's to work through with my husband. I was sceptical about hypnobirthing but I found it very useful in my last trimester for keeping my mind calm, when I was feeling anxious about the birth. However, during labour, everything I learnt went out the window!
NCT however was worth every penny. It's true that the content isn't always that extensive but it was enlightening and it does make you consider things you hadn't thought about before. But honestly, the real reason it was worth it for me, was gaining that support network.
At the time, I didn't think I would click with the people in our group, and I thought it was nice to meet them, but we probably wouldn't stay friends... but something happens when you have a baby, and there are other people around you in the exact same boat, going through the exact same thing at the same time... you really bond... and there's nothing like being able to whatsapp some-one at 2am who's also struggling with breastfeeding when everyone else you know is asleep.
I don't have any family close by, and my friends just weren't going through the same thing, so it really made a big difference to me, especially in that first year of maternity leave. Apart from supporting each other through the difficulties, it's nice having a few "in-built" mum friends that you can do things with. Out of 8, I've stayed close with 2 and our kids are now real friends. I didn't think I would get that much out of NCT, (I was also sceptical about the course content!) but in hindsight, I'm so grateful I did it.
Before you give birth, you're so worried about it, that's all you can focus on... but I actually found the recovery and all the things you struggle with when you have a newborn harder to deal with than the birth itself, so the support network really helps in the weeks and months after the birth.
If you're worried about preparing for labour, I would recommend looking into any antenatal courses that your hospital offers (they are usually free on NHS) - I did my hospital's antenatal course, and that really helped ease my mind a lot. Also, I would recommend water birth for pain relief... even if you don't want to deliver in the water, just labouring in the water helps!
Sorry - I know I've rambled on a bit now, but hopefully you'll find some of it useful :)