I do remember seeing this site some years ago, when I think for London it was tube only - it's been added to since then. How accurate or up-to-date it is, you can form your own opinion. It seems to be an original creation, based on looking at pictures, rather than copied as data.
It does demonstrate the French talent, or enthusiasm, for producing detailed network maps in true vector form. I have some old (ca. 2001) PDF bus maps I couldn't really print at full resolution on what was then a professional A3 inkjet. By "true vector" I mean that, no matter how much you enlarge by zooming in, you never see any pixels or fuzziness. With this CartoMetro one I was surprised to see that that wasn't true (for the PDF) on-line in Firefox. However, downloading the file (and it's only 1.1 MB) to view locally it does work properly.