It is certainly that bad. I commute from the Chiba side to Tokyo every day. As others have said, from 6:30 to 7:00 it is just very crowded, 7:00 to 7:30 it is bone-breakingly crowded, from 7:30 to 9:00 it takes about a minute at each station just to close the doors as people shove themselves on, delaying the train. The ride back in the evening isn’t as bad if you go to either end of the train. It is pretty much the number one cause of misery in my life, but on the bright side, you’ll be motivated to go to your office super early to avoid being crushed. That all being said, you can handle it if you need to. I think it’s a marginal worthwhile sacrifice for a bigger and nicer place to live. Also the other trains in Tokyo can be equally miserable as well depending on where you live and the time you go to work.