This creature can still be frozen, stasis'd, SowQuintReflected, Mutated, and RT'd.
The negative HP is to stop it being so easy to murder.
If you're worrying about gravity pull, don't; it'll go away the second the death effect triggers.
Shrodinger's cat is arguably the worst card in the game, and as a result calling this card more powerful says next to nothing.
Given these factors, I would hesitate to call this card OP. More powerful than it should be, yes...
It'll raise the ATK of both cards to -10 and each card's HP to 1.