So many items, so many changes. I like most of them, but not some.
Also, some new items look definitely niche.
For all people that haven't figured it out yet, a hint: the most meta impacting game change is the Oracle.
Just some side notes: big nerf to Zeke's, reasonable change on Aegis to make it grant def stats only, DFG is good again, QsS has an AD only upgade -Mercurial Scimitar- (good for melee, kinda op on ranged ADCs), Lich Bane now deals magical damage, so it benefits from mag pen, Rageblade look even better hybrid champs, new Gunblade is worth it's cost, (Ruby) Sight Stone will probably be #1 must buy item for supports, Eleisa's may be very good depending on Clearv and Heal CDs, Mikael's Crucible looks OP as fk, Kage's Last Breath looks very flaxible (read strong), Hunter’s Machete seems like no-brain almost-compulsory must buy jungle start, Liandry's Lament is based on current health so meh, Frozen Fist may be good on some champs if someone else in the team has already purchased FH aura (curious about how powerful that passive will be), Statikk Shiv may be good on some champ or just trash depending on his passive, Zephyr may be niche but it's strong (hello Jax), Ohmwrecker + Banner of Command is gonna be hilarious (hi 'Mumu/Malph/Cho), Tiamat/Bloody Hydra, Hurricane and new BC have already been widely discussed, same for penetration mechanic changes, WB SotD, good change on Abyssal aura (many mages have between 600 and 700 max range), deserved nerf to PDs MovSpeed, farewell HoG we loved you, Doran's Ring you look a bit 5h177y now, hello tier 3 boot upgrades (Captain good for initiating, Alacrity overall good, Homeguard maybe for jungling and when sieged but meh, Furor smell OP, Distorsion even more).
Whatever... Time to go on PBE, test some of this stuff and play Nami and her imba AoE stuns and knock-up slows.