As per the email, Rocksmith+ is “an interactive music learning subscription service” which intends to “[take] the guesswork out of music mastery”.
It’s a subscription service that will add new songs and features as time goes on; your subscription will give you access to ‘more music than ever before’, including many sub-genres, too.
“Learn to play acoustic, electric, or bass guitar with Rocksmith+, the only subscription service that offers interactive music learning using official song masters and personalized real-time feedback,” says the trailer description.
The game will be able to leverage your mobile phone as a microphone to pick up your guitar and bass-playing in real-time.