Too simple for The Register readers?
From the comments so far, I think the average Register reader must prefer something more complex!
I see this announcement as simplifying the installation, so that anyone capable of installing NOOBS or Buster on a raspberry Pi can now get a full-blown appliance.
One catch not mentioned in the article is that this is for Raspberry Pi 2/3/4, it does NOT work on Pi 0 or 1. Due to the different CPU architecture for Pi 0 and 1, Ubuntu Server does not run on those devices, and the appliances are based on that plus snap images. I suspect too that Pi 0 and 1 might be a bit underpowered, but might try NextCloud Pi on a 0 sometime.
It's certainly convenient to have the auto-updating snap packages so it stays up-to-date. Of course you have to trust Canonical and Nextcloud, but you are doing that already if you run their software.
Re PiHole - Adguard Home has a comparison of features https://github.com/AdguardTeam/AdGuardHome#comparison-pi-hole - I'm sure our lovely commentards will comment on the accuracy of that list.