A filter is only as secure as the password it uses. It is not uncommon for members of the family to find out or figure out the password. WebChaver cannot be disabled by a password, it logs everything continuously.
Many filters are weak and can be bypassed by anyone with a little computer know-how. WebChaver is extremely difficult to bypass even by the advanced techie, and most importantly - any attempts to do so are reported.
Statistics show that some (blacklist) filters fail to block as much as 30% of inappropriate and even pornographic sites. The more common keyword filters (that tend to slow down connections considerably) still miss as much as 5% of inappropriate sites (equivelant to millions of websites). They can also easily be circumvented with innocuous sounding search terms (WebChaver reports any search terms that result in high-scoring results).
Filters (especially the stronger ones) can slow down your computer speed by as much as 85%. The Covenant Eyes software that WebChaver uses is designed not to affect your browsing speed in any noticeable way.
Filters have been found to block 6 -10% or more of material that they should not block. This causes frustration when legitimate sites are not available. Stanford University News Release (Jan. 2003)
The line drawn between appropriate and inappropriate sites on a filter is not decided by any Rav or Daas Torah. It is an arbitrary standard decided by some company or university. Many sites that they consider permissible may be terribly damaging in a Frum home (e.g. Video and movie sites, gossip sites and blogs etc.). WebChaver puts you in charge of what parts of the Web are viewed in your home and which are not.