If you can't hit anything with it, you probably answered your own question. Few things more dangerous than a gun that you can't shoot properly. Usually that applies to people trying to shoot guns that are too powerful for them, but the same rule applies to crappy little guns too.
Personally, I'd try different ammo with it and see how that works. Maybe try some short or subsonic loads.
As for the rounds slipping out, you could try applying a little blob of hot wax to the side each round before chambering it. That could make reloading the thing tough, but it's not exactly the kind of gun you'd carry extra ammo for anyhow. If you're in a firefight and need to reload your 22 derringer, you're probably on borrowed time in any case
The only tiny revolver I've had personal experience with was a little .25 5-shot pocket revolver, dunno what make/model. It kicked like a mofo, but at least it shot straight. If it was mine, I'd buy some weak loads so it wouldn't numb my hand if I had to use it.