To be honest, 1JL, I don't think you're missing much. Certainly not with the Core package. The main 'benefits' for me were access to the text commentary, photos and videos. Things I had access to before TAG came along. All of which I can still access without logging in to TAG.
If I had actually paid £60 for this service rather than getting it 'free' with my season ticket, I would be really p1ssed off.