How does one do that then?
The publicity photos (and even videos) can only show you what it looks like, not what it feels like.
The only way you can tell if the upgrade is going to make you sick is to try it for a few hours.
- A brief poke in the pub won't help unless your symptoms are acute.
The only way you can try it for a few hours is to upgrade, unless you've got a friend happy to give you their phone for a day.
So the only way to know if it's going to make you sick is to upgrade it and try it.
Once you find that it's awful, then what?
All other smartphones and computers can be rolled back at will - not always easily but it is possible without preparation prior to upgrade.
iOS devices cannot be rolled back once the public release occurs, unless you take specific steps to keep the old keys before upgrading.
These people are not developers, they are not programmers or hackers, they just want their phone to work without making then sick.
Excessive animations are well-known to cause nausea in some people, which is why every single other OS allows you to turn them off.