Everything is changing! Season 1 is starting, and sweeping changes for every champion.
There's also a new 'survival' mode, where the aim is to dodge poison gas and get to the centre of the map, single life.
There's a new currency, essence, which will be used to unlock the pre-exisiting cards and also new powerful legendary cards. This has split the community a bit and might scare off new players as this is a new barrier to entry to anything but casual play.
I think overall it looks great! Hi-rez have been super good listening to feedback in the past and, as you can see, they make loads of changes to the game regularly