I'm not sure saying "some features may not be available" is right, because it implies you may lose some feature/functionality, and that you'd be better off enabling this. In reality, you are not losing any feature, you just lose google fonts and are stuck with standard fonts, right? Not really a big deal IMO.

I think the original quote is probably fine. Perhaps asteriks it or add a link to the Docs or something where you can get more specific about what files are served through this feature (jQuery and Google Fonts), and what there is to gain (or lose) by enabling/disabling this feature.