Sorry for joining the thread late, but thought I'd add my $0.02 -

I used LeFrenchMobile for a data SIM for my iPad back in May. It generally worked okay (only 3G, no 4G) and it absolutely saved the day when I tore a huge gash in my rental car's tire. My phone and my wife's phone (which worked throughout France) couldn't connect to Hertz France's support phone #. After 1+ hours, I had the idea to use Google voice on my iPad to connect my cell phone to Hertz France, and it worked great.