Let me start by saying I like this idea. Paying one monthly sub and getting access to all the games by a particular publisher is a nifty idea.
SOE's All Access will roll out on the 23rd of April. The FAQ was recently revised and can be found here.
There's a lot of info so I would encourage you to read the above linked too FAQ for info.
Basically for new people you'll get 500 Station Cash every month you can claim in the games market place, a 10% discount on market purchases and "Access to exclusive promotions and offers throughout the year."