Teachers signed up for the flagship masters course developed especially for the profession have "major worries" about how they will cope with the workload, a TES survey shows.
More than two-thirds believe the masters in teaching and learning (MTL) is "not compatible" with the job.
The course, designed for NQTs, has been dogged by problems since its inception.
The start was postponed because of delays in agreeing funding, and there has been a lack of support from unions and headteachers.
It is only open to NQTs in the North West and new teachers working in National Challenge schools in other parts of the country. The North West students started in January, with the rest due to begin this month.
The latest figures show that barely half - 2,182 - of the 4,000 teachers eligible for the course have so far signed up.
Sixty-eight per cent of those who responded to the survey said they were concerned about workload. Of those who had started the course, 29 per cent said it was "not enjoyable and not helpful professionally".
However, 70 per cent of the 235 respondents said the course was a good idea. Of those who have started studying, almost 40 per cent said it was "not enjoyable but useful professionally".
A small number of headteachers responded that they had banned their staff from signing up for the MTL because they thought it was "inappropriate" for new teachers.
Funding for the course is only in place for one year. The new Government is yet to confirm whether it will fund it in the future.
John Bangs, head of education at teaching union the NUT, said the survey showed that only offering the course to NQTs was a "daft idea".
"The course should have been for people 15 years off retirement - the group which has the least access to CPD," he said. "These are the people who need reinvigorating."
John Forrest, an NQT at Farnley Park Maths and Computing College in Leeds, signed up to the MTL to enhance his career prospects. He is concerned at how he will cope with the extra workload.
"It's a major worry," he said. "Our senior leadership team wants to raise the standards of teaching, and I don't know if the extra work will be counterproductive.
"We were told it wasn't essential to do the course, and a few of us decided not to because of the workload. But I thought the positives outweighed the negatives."
Philip Smith, an NQT at Seaton Burn Community College in North Tyneside, starts the MTL this month. He said having nine months of teaching experience behind him would make it easier to combine the course with work.
"I want to keep on being reflective and the course will help improve my teaching," he said. "Completing essays will add a lot to my workload, but this course is funded and it's better than a masters in my subject - science - because it covers teaching."
A spokesperson for the Training and Development Agency for Schools, which is responsible for teachers' professional development, said: "A masters qualification will always demand additional work. It is pleasing to note that the majority of respondents to your survey are of the opinion that the MTL is a good idea and that the participating teachers' work on it will enhance them professionally, which is its intention."
68% of respondents to the survey said they were concerned about MTL workload.