Well, a lot of items are getting swapped around, but its really jungle items and pots that are getting altered. You can have 1 pot type, they are refillable, jungle items no longer give regen and we got one that gives a ward, and another that gives pots.
on the ADC end, Essence Reaver gives CDR based on crit and a number of itmes have been changed. Many items, almost at random, have been given little bits of crit, so a lot of non adc champs will actually have some, same for lifesteal iirc.
basically they are looking to up everyone's damage and sustain so to match up with juggernauts and hopefully keep adcs from getting as ridiculous as they used to be.
Also Graves is the most broken pos right now omg.