Rated 3 out of 5 stars
It was a great add-on in its days. I stopped using it because I saw no purpose in using Web Search Pro, since Firefox can do practically the same thing on its own minus a couple of options. Add to Search Bar and Organize Search Engines are a great addition to Firefox's already built in features. If you really want Drag & Drop Zone then you can install the add-on. I use Auto Context along with it as well. The other reason I stopped using it was I was tired of having to submit if I wanted a site added (I like instant gratification, Add to Search Bar).
I see no reason to add an add-on who contains features that Firefox already has. Why bloat a system! Yes you can disable features of Web Search Pro, but the usage space is still there, allowing for more reasons your system to become fragmented. Not to mention the possible conflicting that could be caused with other add-ons or new ones the dev might not yet have had the chance to analyze yet. In my opinion that is one of the top reason add-ons do not always work how they should is overlapping code.
Now if you can honestly tell me that Web Search Pro uses the already built in code Firefox's search functionality uses (i.e. suggestions, quick keywords) then I would be apt to re-consider. Truthfully I would prefer an all in one Add-on (or at least the option of AIO or Individual in case I don't want all the features (not bloat my system with them only to just disable them).