Season 5 Yi is confirmed OP AS FUCK; which I love
Skirmishers saber gives 69 true damage (very funny Riot) on hit at level 18, while reducing damage done by the target that is smited. If you farm decently (and even gank well, thanks to its passive), the devourer enchantment to the jungle item can do around 100 magic damage per hit at around 25 minutes (this enchantment is like a Feral Flare, but on crack). You get 50% attack speed, so you can spend money on Merc Treads for the tenacity, without losing the necessary damage. Overall, Yi's one jungle item should do around 40 something true damage per hit to a smited target for 6 seconds, around 100 magic damage per hit, reduces a target's damage to Yi by 20% for 6 seconds, and gives 50% attack speed at around 30 minutes. That is RIDICULOUS. And ALL OF THIS only costs 2,250 gold. Just one item slot for 100 magic damage, 40 true damage, 50% attack speed, and 20% damage reduction. The rest of the slots can still house Yi's core item build (with the added Merc treads instead of the normal berserker greaves).
Confirmed, Yi can fuck some people up HARD now. I guarantee, he will be on one of the next few nerf lists (or the item will).