Babies and bathwater
Although ForceField does an okay job on its own when deciding what to keep and reject, it was occasionally fooled, sometimes getting rid of items I thought were more permanent and vice-versa. For example, it consistently reset my personally selected home page, but left maliciously installed programs alone.
ForceField did stop many malicious Web sites from loading and many malicious programs from being installed, although its own count seemed unrealistically elevated. For example, it reported stopping more than 16,000 threats from the first seven sites I visited, but my network sniffer showed the true number to be below 60. I'm not sure how ForceField is counting threats. Plus, although ForceField did prevent many malicious Web sites from loading, it would often simply caution me from inputting personal information on the site I was visiting, when in reality the site was trying to inject me with malware and never attempted to collect personal information.
There were many false negatives, where ForceField failed to report anything suspicious when malware was definitely present. ForceField also failed to prevent a number of malware infections. One rootkit was installed as a service, and several others installed using malformed multimedia content. ForceField would allow me to install many common browser add-ons, but prevented me from installing legitimate new language packs. Browser performance was significantly affected overall, and often the browser seemed locked up or had to be prodded with multiple reloads to finish displaying the requested page.
ForceField has some other interesting features such as the Private Browser option, which blocks cookies and allows you to browse the Web without an audit trail, keeping the browser history, file download list, and other local trackers clear of evidence. You can also open an unprotected browser session. ForceField is obviously a consumer-focused product as it lacks enterprise management features, detailed logs, reports, and almost any type of granularity.
ForceField is a good companion product to the ZoneAlarm Firewall. I tested the latest version of ZoneAlarm against the same malicious Web sites, and ForceField blocked more than the firewall component did on its own. By the same token, the firewall offered some protections that ForceField alone does not provide. For instance, the firewall blocked many outbound communication attempts by malware that slipped by ForceField, and alerted on a few malicious Web sites that ForceField didn't detect.
More telling in the grand scheme of things, ForceField proved less effective than a fully patched version of Windows XP SP3 running Internet Explorer 7 and fully patched applications. Exposing the patched system to the same malicious sites I used to test ForceField, I discovered that all malicious drive-by-download programs were prevented even when the malicious Web sites were displayed, besting the prevention provided by ForceField on unpatched systems. ForceField could possibly offer some detection and prevention advantages for zero-day exploits, and even in my limited test cases, definitely offers improved alerting and detection over a system without any anti-malware software installed. But it didn't provide better protection than a fully patched system.
Overall, I found ZoneAlarm ForceField to deliver slightly above average protection (due to the anti-spyware and anti-phishing detection capabilities) as compared to other security sandbox products I've tested, but I'm still not convinced that any product of this type offers complete enough protection to be strongly recommended.