Simple can sometimes mean better. I fully believe every one should have some variation of a simple pheasant tail pattern in their box. The fishiness is in the pheasant tail abdomen, and the lightly flashy, but otherwise natural thorax compliments this feature rather than stealing the show.
The dark variation is a great winter(or other small dark early season) stone and black caddis pattern, but I also feel it imitates the darker cylindrical cased caddis. This one is a particular favorite during the colder months. The natural is a good all around generic color great as a searching fly year round.
Frenchies are sick. Hot spots are dope. But the basic Pheasant Tail nymph is timeless for a reason.