You get a welcoming kit that includes a set of chalices from Stella Artois and is essentially an exclusive club. One of the rewards:

"One of the level Deux rewards of this month is to have exclusive
access to Heidi Klum's Halloween party."

You could easily redeem for free dinners/sports tickets/free movie showings and the like.

You need an invite to join and is limited to 30,000 people total. Anyone who doesn't sign up early enough will be put on a waiting list even with an invite code.

Here's a few codes to get you all started:

5758TKY

6667LNO

1478KNS

6225QOR

4796FWT

9970NNF

La Societe