The report is discussed here and here. The full report can be downloaded here. There is a lot in the report and I think it does a good job of bringing up a number of central concerns such as what to do with people that can't be convicted of any crime but are suspected of being dangerous.
The report, correctly in my view, points out how dangerous such preventative incarcerations might be and how open to abuse they are. But the question still remains. For instance, Nasir al-Wahayshi, the current head of al-Qaeda in the Arabian Peninsula, was never charged with any crimes and was being held only on suspicion of attacks he might commit in the future. I don't think the argument that al-Wahayshi was radicalized in jail holds here, that is, if al-Wahayshi had not been arrested that he would not now be planning and directing attacks.