It's missing containers and overall has less privacy features available than firefox.
This is exemplified compared to forks like librewolf that enable the majority of them.
Ungoogled Chromium and stock Firefox are pretty similar privacy-wise though.
The main advantage is all baked-in telemetry is stripped out, but it doesn't do much to protect you from privacy-invasive sites other than disabling WebRTC and blocking 3rd party cookies.
I used it for a number of years, but recently switched to Librewolf ~5 months ago and don't expect to switch back unless Firefox and all downstream forks completely implode.
It can run ublock origin right now, and will be able to run ublock origin lite into the future.
No chromium-based browser currently plans to keep MV2 support. It's just not feasible for a small group to keep it maintained ontop of the inevitable breaking changes that will be introduced in upstream over time.
If this bothers you, use a real browser that isn't sourced from an ad company.
Otherwise, you'll be getting exactly what you should expect, and nothing more.
Ungoogled chromium is a good alternative in terms of privacy because all google-related services are gutted and there are no other built-in telemetry things.
There are some downsides, too.
First, you have to do some research on learning to make this browser work conveniently, e.g. finding alternative services to sync and backup your settings, bookmarks, accounts and passwords, etc.
Second, changes pushed by Google like Manifest V3 is still hard to deal with.
