If you are hard core meta (which isn't needed in lower ELOs), you pretty much want a support that can heal/shield because of Ardent Censer. The item itself has had some changes over the past few months (but is pretty much the same as it has been). BUT with the ADC meta lately...specifically AS champs that can get even more out of Censer, it has become the latest must have item.
Janna was the main culprit (of its use) and they have tried nerfing her, but with Worlds going on, they don't want to change things too much and mess up the pro's current idea of what the meta is, SO she is still broken and picked/banned in every pro game and many higher solo Q games. And Lulu is being picked opposite her more often than not.
We have this new honor system. You start at level 2 and work to 5. it's slow, so don't wonder what takes so long. Once you get to 3, you get some load screen flair if you were honored in the last game. You can only honor 1 person now (3 new categories, which are aimed at player attitude (rather than skill, though most ppl still honor carries, etc)), and you can't honor the enemy team. You will get key frags through the honor system now, but no one really knows how it works. They randomly drop. You can also get Honor Capsules (chests) once you hit H3, and those also drop randomly.
The upcoming season will have a totally new mastery/rune system. I haven't looked into it much myself yet.
Couple new champs and reworks...the usual.