Ofsted's new inspections, which are carried out at short notice, take less time, and make greater use of the school's self-evaluation, have been broadly welcomed by heads.
A report by the schools' watchdog said that nine out of ten heads were content with their reports and 80 per cent believed the new regime, introduced in September, was less stressful.
Ofsted acknowledged concern from heads about the use of school performance data by inspectors.
Heads have protested that some inspectors make their minds up about their school before visiting, based on indicators including "contextualised value-added" data. Ofsted said it had "reiterated its guidance to inspectors that this data should inform but not determine inspection judgements".
The report also concludes from its survey of heads and quality assurance visits by HMI, that most inspectors are of the quality required, "although there is no room for complacency".
The report said: "A very high proportion of headteachers and authorities reported that the inspections had recommended a sound and appropriate agenda for school improvement."
It said self-evaluation - central to the new inspection framework - was improving, and that the self-evaluation form was considered "helpful, if time-consuming" to complete for the first time, by most headteachers.
There was less consensus on the new four-point grading system. Just over half (54 per cent) of heads approved of it. Some heads were concerned that schools previously judged very good are now merely good.
Ofsted said that the number of complaints in the first two terms of the new "Section 5" inspections were similar to the number under the previous system. Most complaints were about the validity of the inspectors'
judgements and their conduct.
The new system has significantly cut costs for Ofsted and schools. The average cost of a Section 5 inspection to Ofsted is estimated to be pound;9,300, compared to pound;20,000 for the old Section 10. A survey of heads inspected in the last term of the Section 10 framework found the estimated cost ranged from negligible amounts to pound;36,000. Visits to 15 schools inspected under the new framework suggested that the cost and workload had been reduced.
The report said inspectors needed more guidance on how to evaluate Every Child Matters implementation. Inspectors will also have to ensure that schools have full details on the qualifications of staff and that all criminal checks have been made.
A separate study by the National Foundation for Educational Research, Impact of Section 5 inspections, based on 134 schools, including 36 case study visits and interviews with senior managers and governors, backed Ofsted's findings.
More than half were very satisfied and just under a third quite satisfied with the new framework. The completion of the self-evaluation form was viewed positively by the vast majority and self-evaluation was now seen as an integral part of school development. Just under two-thirds thought the process was less stressful.
Most believed inspectors accurately identified school strengths (81 per cent) and weaknesses (72 per cent). The NFER found that some teachers were disappointed they not been inspected. Others felt there should have been more time spent on lesson observation.