I got their regular Tracking Card a while back when it looked like they had a pricing error (they honored it or maybe didn't catch it before it shipped) unlike my AirTag purchase attempt last week (Apple cancelled it).
It has the same issue like any other non-Apple tracker that others have pointed out: no precision finding. It's nice Bluetooth has a very long range but if I left it in my car and I go into a restaurant, house or some other building within range, Find My says the card is with me. If I really did lose it, it'd be really hard to find with Bluetooth only within some 100 or so meter radius.
One thing that other non-Apple trackers might be better on is the speaker volume. It's not very audible if it's in a wallet that's under a pillow. Forget it if you're in a more noisy environment.
Overall, I feel non-Apple trackers aren't very useful other than confirming you left it at home, work, etc. long after you've left.
I've been hoping with the announcement of the AirTag 2, Apple also announces a card form factor with precision finding or licenses it out to 3rd parties.