It's a nice piece. I think in the past, the wallets were considered tough to find, but I think there was a find of these in the past few years. They are not too tough to come by nowadays. Unfortunately, I picked up a couple prior to this find. As far as opening it, I don't think it's going to affect value too much if you open it, especially since it's just a plain plastic bag. It's pretty nice looking when opened up. Here's a pic of one of mine to show you...
Edited to add: My only concern would be the plastic cracking when opening. The one I pictured had been stored flat for many years. If the plastic on yours still feels soft/pliable, I would think it would be OK.