Utterly gripping. Being able to listen to the back room talkback loops is key. The fact that they've made the effort to sync them all up on a timeline makes it more real. We put it on the proper TV and listened for about four hours yesterday.
It helps if you've learned the listening-to-three-conversations-at-once trick of talkback. The transcript only covers what was on the main Flight Director / CapCom / Public Affairs mix. Much of the real work is on the EECOM and GNC loops which aren't on the transcript so you have to actually listen.