Works exactly as described! My only gripe is that, as someone else mentioned, it does break google maps (and several other of the seamless search features you don't even think about but will definitely miss). Although, you can toggle the extension off easy enough if you do find yourself having some kinda Google issue.

However, all it truly does is append "-site:pinterest.*" to the end of any search phrase you put through any Google field with reckless abandon -- which is why it breaks things like Google Maps and some of the richer features offered as a first result when googling for definitions, translations, or unit conversions.

I don't know that I'll keep it installed to be perfectly honest. I'm pretty sure this add-on could be replaced with a bookmarklet or by simply adding a second Google as a new custom search engine with the earlier string in quotes added into its search URL template.

Might be worth keeping to use for mobile though.