I really used it. There are parts of the mountain that are near 12 percent grade. It's also a narrow road, so there's no stopping ... unless you can clip back in on a steep grade. I had a 12x23 in back, by the way.
I didn't sleep a wink the night before Ventoux. L'Alpe d'Huez was a comparative picnic. Ramaz was easy. Galibier (except for the last km) was fun. Ventoux was hard work. But fun. Bring your plastic or some Euros; you'll want to buy your medallion when you get to the top. Bring your camera, too. (Obviously!) And the ride down the other side, on beautifully paved road, is a rush. We hit 50.
Good luck!