The new-beta-UI is horribly broken in terms of usability, usefulness and especially effectiveness of use. Most daily admin tasks are hidden behind some fancy-animated icon which doesn't have any clear meaning.
At some point all admins will be forced to use the new-beta-UI and given it's current appearance it will make most of our daily tasks take twice as long since we have to wait for all the unnecessary eye-candy which appeals to marketing departments but is a blocker for actually working with one, two, or 12 FreeNAS boxes.
If you compare the amount of clicking and waiting involved for the very same tasks in the currently-working-UI (aka old UI) and the fancy-but-unusable-beta-UI you'll immediately notice that it takes at least twice as many steps to achieve the same goal, if possible at all.
The information to get a good overview over running services, Volumes, Jails, Plgins, anything easily fits on a 15" laptop screen when using the old-UI.
With the new UI, it's impossible to do that because of all the fancyness that is unused space. (Not helpful, view guiding and structure providing white-space, but wasted useless widgets, borders, margins, etc.) It's pretty much unusable without a 27" monitor.
(I guess devs are working with (multiple) 4K screens and just don't notice they're designing a UI that is absolutely not suitable for the tasks and use-case their target audience actually has.)
Those tasks are working locally or remotely, via VPN or SSH, from a laptop.