Locked down hard, meaning you get completely vendor-locked-in, and you can't install alternative OS (there is none I think) or even apps from different sources without voiding warranty or using unsupported, unreliable hacks like jailbreaks for specific models.
Privacy-invading. Sure, not as bad as proprietary Android distros, but still far from privacy-respecting
Account-bound. Everything is tied to your Apple account. To even set up or use the product you need an account.
As proprietary and closed source as it gets
Ridiculously overpriced, so very low value for the money
The company is known for its anti-competitive and monopolistic, even mafia-style behavior (e.g. when insisting on their 30% cut for all apps, insisting that apps use the in-app-purchasing system and not allowing "subscriptions from outside of Apple's ecosystem", stuff like that. If app developers don't comply with ridiculous rules, they get their apps taken down, and since the AppStore is the only source for apps, this means they have 100% control and can kill any app which they don't like or which they perceive as competition for Apple's own apps.
Use GrapheneOS. It's a secure, fully privacy-respecting open source distro of Android (based on the open source Android) without any Google services/apps by default, but with full Android app compatibility.