The philosophy between lanes (And the jungle) is largely unchanged, but new items and other changes have made the playing a bit different.
Top: Still mostly for Tanks/Fighters who can sustain for a long time on their own. Ignite isn't taken much anymore - Buffs to Teleport made it a more attractive option so top laners can gank bot or come help with dragon. It's also played by a few ranged Mages, but they're often burly and have ways to keep themselves safe.
Champions to consider: Sion, Renekton, Maokai, Lissandra, Morgana, Ryze, Cassiopeia, Hecarim, etc.
New items to research: Righteous Glory, Zz'rot Portal
Jungle: Got massive changes with the new season. The jungle was made much more punishing - Camps hit harder and have more hp. However, jungle monsters also now have bonuses when you smite them. These bonuses are mostly buffs that make clearing the jungle safer and easier. This is to promote junglers actually jungling, rather than being complete gank machines, and to discourage laners taking camps. This makes junglers with high sustain more powerful. All of the camps, with the Summoner's Rift VU, are also different.
Small golems -> Krugs: Smiting them grants Gift of Heavy Hands, which makes your first and every 6th attack stun a neutral monster.
Wraths -> Razorbeaks: Smiting the big bird gives a buff that alerts you and grants truesight when an enemy ward is nearby.
Elder Lizard -> Red Brambleback: Smiting restores a portion of your missing hp.
Wolves - Murkwolves -> Smiting releases a nature spirit that wards the nearby jungle and pings the map if an enemy enters the jungle.
Ancient Golem -> Blue Sentinel: Smiting restores a portion of your missing mana.
Wight -> Gromp: Smiting grants Gift of the Toadstool, which poisons enemies who attack you.
In addition to camp changes, the old Spirit items have been replaced with jungling items that enhance smite.
Stalker's Blade: Allows you to smite champions, dealing a small amount of damage and stealing 20% of their movement speed.
Ranger's Trailblazer: Causes smite to deal AoE damage to nearby monsters, stun them, and restore a portion of your health and mana.
Skirmisher's Sabre: Allows you to smite champions, revealing them, reducing the damage they deal to you by 20%, and making basic attacks burn them for true damage over 3 secnds.
Poacher's Knife: Smiting a monster in the enemy jungle grants bonus gold, a reduced smite cooldown, and movement speed when the big monster dies.
Champions to consider: Lee Sin, Rengar, Nidalee, Vi, Jarvan IV, Rek'sai, Warwick, etc.
New items to research: All the new jungle items listed.
Mid: Still most valuable for Mages and Assassins. Probably the least changed lane overall. Still often gets Blue buff from the jungler. Deathfire Grasp was removed from the game.
Champions to consider: Orianna, Zed, Lissandra, Morgana, Ahri, etc.
New items to research: Luden's Echo (On PBE), the removal of Deathfire Grasp
Bot: The ADC and Support combo is still what works here. Largely the same, but dragon is a much more important objective nowadays (More on that below). Some items got changed - Bloodthirster now grants a shield when you overheal with Life Steal.
Champions to consider: Graves, Kalista, Caitlyn, Varus, Corki, Leona, Braum, Thresh, Annie
Items to research: Righteous Glory, new Bloodthirster, new Mikael's Crucible
Other changes: There were a lot of new changes to towers and epic monsters as well.
Second tier turrets now grant champions a shield when they stand nearby, and have a small shield that blocks champion damage (Not minion damage).
Outer base turrets now fire a laser instead of shots that has higher ramped up damage.
Dragon no longer grants global gold - It now grants a stacking buff that gives bonuses with each dragon slain. In order, you get 6% increased AD and AP, 15% increased damage to towers, 5% increased movement speed, 15% increased damage to monsters and minions, and, upon the 5th slain dragon, a temporary buff that doubles all other bonuses and makes attacks deal bonus true damage.
Baron Nashor is now a 'siege' objective. It still grants global gold, but now also grants a buff that empowers lane minions, making them tankier and deal bonus damage (Siege minions in particular gain MASSIVE range). Also it cuts recall's cast time in half.
Certain items were reworked or changed. Banner of Command now grants a particular buff based on whatever minion is empowered, and makes that minion immune to magic damage. Warmogs grants higher health regen when out of combat. And other things you probably want to research.
Any questons?
