Like any education system it depends on the student, nec encourages independent learning and study skills which to people who are used to being spoon fed at pre-gcse/gcse level may have not liked; but it is to get you prepared for university.
Saying that your tutor is only an e-mail/phone call away. Like any teacher some you will get on better with others. They give you your teachers profile at the begining and a lot of them that I had at least had also been through one distance learning institution or had been teaching for many years prior to joining nec. So they really know what your going through.
It is very different from the OU if you have studied with them, esspecialy now as most of the OU courses are becoming online only and has digital planners and tracks your progress for you. You are going to have to do this your self with distance GCSEs.
Yes I did get a huge folder to work through at my own pace with nec, but it broke everything down to a specific number of hours for each chapter. But I had to estimate and plan by what month I wanted to be where. They do give you a guideline though.
The course materials were very well designed with very clear instuctions on how to do any maths with a huge bank if questions to practice with and all the answers. If you needed an answer explained the tutors were well prepared for it.
And if you still had problems you just message the tutor, they really dont mind its what they are payed for!
There are assignments that would test your learning that my tutor was both quick at marking and gave good explanations where to earn more marks.
My A-level biology tutor via the nec was actually better than my S111 tutor at the OU.
Maybe the real question is not if [insett and distance provider here] is good.
But what kind of learner are you?
All these questions are relevent for any course anyone is doing.
For example:
Can you plan your own learning?
Can you work through instructions or do you prefer someone to stand there and explain it?
Will you ask for help if you need it?
Do you know what grade you are aiming for?
Do you understand that it is you taking the exam and not your tutor and you are responsible for ensuring you are prepared, not the teacher?
Sorry if it sounds patronising but no matter who you pick it will be down to you how well you do.
Hope this has helped.