Basically it's the same thing SiteAdvisor is.
It has the ability to go directly to HouseCall for a free online virus scan built into it, so that's kind of cool, well sort of.

It also has the ability to flag advertisements as baddies in the Options->Content Categories.

It doesn't have that special page which SiteAdvisor has which gives more info about a link, such as green downloads, etc., why a site is considered "bad", or what sites link to a particular site.
It does have a rather obvious little "icon" displaying in Firefox that's going to take some getting used to,
as seen here.
I am however going to leave SiteAdvisor disabled for a few days to try out TrendProtect more thoroughly.
Note: You'll want to track the installation with ZSoft Uninstaller or Total Uninstall since it doesn't install like a normal Firefox extension, it's a fully downloadable .MSI installation package that does place some files in places one wouldn't expect like in the root directory, i.e.; C:\