Both CNET and PC World criticized the suite's relatively high retail price, US$79.95. Features such as parental controls and instant messaging protection, found in competing suites from Symantec and McAfee, were not a part of version 6.0. The magazine found the graphical user interface to be awkward to navigate. The firewall blocked all attacks from inside and outside the computer when tested. However, data is cached from each scan, making each subsequent scan faster. PC World also highlighted the suite's false positives - eight of 20,000 clean files were incorrectly flagged as malicious - and its noticeable impact on computer performance. However, version 6.0 was criticized for not completely removing malware by leaving Registry entries and files. KIS has the ability to scan within compressed or packed files, detecting 83.3 percent of the 'hidden' malware.

The suite detected almost 100 (99.57%) percent of adware samples. KIS detected 100 percent of threats on a subset of the January 2006 wild-list, a list of prevalent threats. PC World magazine praised version 6.0's detection of malware. Version 6.0 was the first release of KIS.