It's a crappy frame, but a good starter. You'll probably not find a harder bike to work on than a vintage french bike. You'll basically want to replace everything, have a difficult time sourcing new parts, and have a hard time taking off the old parts. Join the Chainlink group, Velo Francais, to find out more about the pleasure of working on and riding french bikes.
So in other words...you'll learn a lot!
I'd just keep the gears, crank and seatpost, and buy a new brakeset, handlebars, tires, and saddle.