I can see both sides of the coin.
I didn't do NCT classes myself because they were so horrendously booked up. However, I joined anyway and got very involved in my local branch, started training to be an antenatal teacher with them and so was observing and assisting in teaching some classes. I saw lots of new parents come through the doors. Some of them were disappointed by their classes and felt they didn't get a huge amount out of them. A few felt very let down by the NCT - largely those who ended up with very medically managed births or sections, who felt they had been set up for a 'perfect birth' and 'failed' (this is something lots of teachers, particularly more newly trained ones, are very sensitive to and it is definitely changing within the organisation). The vast majority got something very valuable out of their classes - a friendship network that would far outlast their involvement with the NCT.
My criticisms:
The NCT has got a big image problem, and they (we) know it. It is seen as being quite worthy, a bit too idealistic and not inclusive of all women. It has been trying to rebrand in recent years, but I don''t think it's had much success, in all honesty. It is still seen as middle class, expensive (although this is not necessarily true), over subscribed (very often true) and as an organisation which glosses over some of the realities of birth and life with a newborn (fair comment in some but not all cases, I say).
At local level the NCT is only as good as it's members and it's teachers. It needs the membership fees and practical support of local people to survive and thrive. In areas where membership is low and/or support is poor, the NCT is worthless really. Likewise, in very oversubscribed areas, the customer service can be pretty crap.
The administrative core of the NCT is shambolic and bureaucratic. Anyone who has tried to book a course with them and failed, and certainly anyone who has worked for them, will testify to this.
The process for applying and training to be a teacher is too long winded. It is a fabulous course - without a doubt the best of it's kind - but it isn't always recruited for and run professionally, and that has a knock on effect. There is a general culture of poor communication within the NCT which can be hugely frustrating for those who work within the organisation and those who who attend classes.
All in all, though, the work that the NCT does is hugely important. It's a campaigning charity and a pressure group and people forget that. It plays a crucial role in informing and advising the government and health authorities on antenatal care. We need an organisation like the NCT. It is imperfect but it needs to exist. We just need to work out how to improve the service it provides.