I forgot to ask you how jungle yasuo worked out.
He's better than I thought. Your itemization desires don't really change - you still want IE + SS really bad - which sounds like it would be a complete nightmare, but he has quite possibly
the most blisteringly-fast clear speed after his first back and way, way better lane wave-clear to pick up stray lane farm than just about any other jungler I can think of, so it's not as ridiculous getting him spun up as I thought. You don't generally need to buy Vamp Scepter like you do in lane, so you're not as slow to hit critical mass as expected. You really don't take much damage in the jungle due to the combination of Flow and lightning fast AoE clear; I'm curious how he might work with Feral Flare since he doesn't need Spirit Stone sustain, but that 40% -> 30% gold generation nerf is really painful since his priority is getting his "lane" items ASAP.
He doesn't do "normal" (hide in a bush and wait for a wave to be mostly-dead) ganks very well, but along with Fiora he unlocks one or two ganks that other champions really can't do at all. Specifically, in the long lanes you want to do the exact
opposite of what jungle instincts tell you: you want to lane gank when the minion wave is inbound and would normally provide "cover" for a fleeing enemy, because nothing gets Yasuo's dick harder than a siege minion wave conga-lining down the lane for him to double/triple-dash through.
It's also important to note that on normal clears you'll usually sweep a camp with two Q's and as a result leave with Steel Tempest charged. Most of the time you'll just hold it for safety in case someone surprises you in the jungle, maybe pop it in the direction of the next camp to get some free damage, but you
can quite easily go into a mid/top counter-gank situation with the cyclone chambered and surprise the fuck out of people who think they're safe because you have no instant-demand CC.
The main thing is, obviously, you end up turbo-farming and only want to gank for lanes where you have a lot of CC support from your laner. You
can apply red buff much more easily than most junglers, so the long lanes are always potential gank locations if enemy champions push up too far.
He solos dragon like an absolute boss due to windwall abuse, though his inability to dash over dragon wall means you probably won't actually want to pull that trick very often. It's worth remembering if you have a successful gank bottom lane that ends in a 3-for-2 in your favor, though; you don't really need laner help for dragon as long as you can be sure no one's going to interfere.
Obviously, you still need displacement assistance somewhere in the composition, but with him in the jungle you unlock Lulu/Orianna/Gragas mid options which are more or less the best things ever. Your GA's usually going to be slow, so without someone else to generate the knock-up for your initial ult you're going to feel super useless in team fights, godlike windwall baits aside.
Overall: he's highly-specialized and definitely not for every team composition, but entirely better in the role than he has any right to be.