I can confirm that this new lounge is for real and is as shockingly nice as described by the OP. On Jan 15th I spent some time in the lounge before my EZE-MIA day flight in J on AA. I was welcomed into the lounge as an AA EXP with no issues. The lounge offers a selection of beers (including Antares, an Argentine microbrew), Evian, even Freddo Ice Cream in individual containers. There were perhaps 6-9 iMac computers for public use in the lounge. I was very impressed and will not be frequenting the AAdmirals club, Amex Lounge, or Club Americas Priority Pass lounge again in the near future. I have a TAM J flight coming up to GIG and I hope they will let me in!