Comment by rdl

Lockdown prevents new enrollment in MDM/adding profiles, but you can use an MDM you're already enrolled in. It's pretty good from a security perspective.

What I dislike is that it applies to all devices in your iCloud profile, and is overall pretty intrusive/annoying. Best practice if you're going to use it is probably to have multiple iCloud accounts (maybe in a "family" for license sharing), and Lockdown Mode one of them for the more secure devices. I tried using it for all of my devices last year and it was pretty unusable.

(Main pain point was how it handles unsecure wifi networks; I consider ~all networks insecure regardless of wifi encryption, but not being able to save or otherwise autoconnect to a hotel network with an iPad with nothing on it, etc. was the last straw. With a decent travel router it's fine.)