Yes, Goodison was not like most British grounds and had become more of a "special occasion" stadium for some similar reasons (high roof lines etc)..... and it certainly never had a single large "kop" to help generate an atmosphere. So I'm not sure if its the best comparison for a brand new stadium. However, that said, with standing and seating on all 4 sides, it was always very loud when it had over 50k in it.
I think people are specifically "homing-in" on the South Stand not quite being the more dominent blue wall of noise that they expected, so far. Of course, it's people who make the noise, but the stadium/stand/roof design and how it was marketed to the fans can greatly enhance and even help prompt that. "Ideally", it probably needed to be a true single tier, with another 15-20 rows going right up to the roof in the south stand, giving greater massing and much larger acoustic catchment.
We've probably seen enough to know that the generally the atmosphere will be mostly decent, and great when the occasion/opposition demands it.