Interesting and clever grid, but a little too arcane for my tastes. Well, three quarters of it, because the "12 monkeys" category was a really easy solve.

The remaining three felt like something one could not realistically expect someone else to solve, at least not within 3 minutes. One category like that would perhaps have been ok, but three just makes things impossibly difficult.

For a grid that's challenging enough to be fun, while still remaining realistically solvable, I'd say the sweet spot lies somewhere between the "12 monkeys" category and the other three.

But that might just be me.