Hi Mr. Niels,
Yes. It works and it works good. The only thing to consider is that you ask for the upgrade and you wonīt get confirmation till a few days before departure. They will confirm or not according the availability. If they donīt, will refund the 29€ you paid.
You get Premium class facilities including service in the plane, lounge access, priority in the airport pass, excess baggage, double points...
Enjoy it!