Jarvan is still good. Bear is still as good as he's always been, I think.
Season 3 item changes have happened for everyone. Iceborn Gauntlet is good, Blackfire Torch is now an AP version of Trinity Force in terms of gold cost, stats, and role, various build paths have changed, Executioner's Calling is no longer the OP bastion of lifesteal it was in Season 2, vampiric scepter now costs 800 gold but builds into Grez's Spectral Lantern (which moved over to Dominion,) Lightbringer was remade into a Grez's upgrade, Sweeper and Lightbringer now have an anti-Teemo passive, Zephyr exists but has the world's crappiest build path, Elise is still amazing, Trundle and Sejuani reworks are great, Lissandra is decent and should be taken bot, Zac is good, Quinn is decent, Thresh is **** because of how poorly his soul mechanic works on Dominion, Vi is good, Nami is meh, Zed is weirdly less effective (granted Wooglet's is a thing now,) and the Karma rework is godlike on Dominion despite apparently being considerably less potent on SR.
Nidalee has been discovered and is approaching god tier.