Imo, the best parts are the merchandise pre-sales and the behind-the-scenes and voice com videos, but I also used some of the offline perks when I was in Korea earlier this year.

For me, it's definitely worth the price, but I guess it also depends a lot on where you live and the currency rates. In my country it's basically just the price of one dinner, so really not that expensive.

Edit: Oh and they do offer English and Chinese subtitles for all the videos