I've had this problem as well, but I think it is more my

The only real problem is that you are moreso learning specific songs that you'd probably be able to commit to memory easily, but you won't gain much knowledge of the musical theory associated and you won't really learn to read music, so beyond the specific songs it teaches you (there are a decent amount and you can buy other songs as DLC as with Rock Band

As others have mentioned, lag is a problem

This is a very frustrating problem lots of other users have as well as this very problem is a very frequent complaint in Rocksmith online forums I found when Googling the error message.

Great game, very innovative, and yes you can actually learn to play guitar, only problem is the lack of really good songs.

The default has the low "E" as the top string and this can seem to be helpful at first but it will really throw you off then you start to use TAB books.