No Roberto, it's not as stiff as balsa and glass but it's much lighter. What I especially like is to use paper and a thin glass cloth together. Usually I have used obechi veneer or koto for sheeting foam wings but the paper is only 1/3 of the weight.
My only concern is because the paper is so thin, there is a danger of the trailing edge warping. But thin strip of glass cloth and a little wider balsa trailing edge might take care of that, I hope.
Yes you are right it is cheap, one 50 meter roll of paper cost me the same as 3 sheets of 1,5 balsa. 50 meters of paper is enough for 12 sets of wings so it's almost a joke. A 2 meter wing costs me no more than a new fuel tank so it is affordable if I want to try many different wings. Sure it is the most cost effective and the quickest way to build wings. I'm using Bob Smith Industries Finish-Cure epoxy and that gives me a very nice semi hard finish.