We’re happy to share ISPmanager´s detailed review made by the most reliable and independent international web source on hosting topics. You can read the article by following the link bellow: http://www.hostingadvice.com/blog/ispsystem-ispmanager
It would be right to point that ISPmanager (and even it’s 5th version) isn´t new product on the market, and various hosting resources have been posting material about it constantly. But the case with HostingAdvice is special, because it is one of the few web sources, which are truly independent and reliable.
Plus, since we had a chance to meet with HostingAdvice experts PJ, Alexandra and Ryan in person on HostingCon Global we were really interested to read their opinion about ISPmanager ourselves (and really happy that it's positive!). Have a look at it too, and feel free to share your opinion in comments!