First:
Nerfs that you probably are already aware of -- Small-Time Bucaneer now has 1 health and Spirit Claws costs 2, thank god.
Ladder change that you probably are already aware of -- Ladder will now have "floors" at Ranks 15, 10 and 5. So if you reach rank 15 you will no longer be able to drop from it, for example.
Year of the Mammoth changes --
http://us.battle.net/hearthstone/en/blog/20475356Rotation -- As promised, when the first 2017 expansion shows up, BRM, TGT and LOE will rotate out of Standard.
Individual cards rotating out -- A number of cards will leave the Classic set and become Wild-only cards. These are:
- Ragnaros
- Sylvanas
- Azure Drake
- Ice Lance
- Conceal
- Power Overwhelming
I am going to miss N'Zothing Sylvanas, POing Leeroy and 6 damage Ice Lances.
Dust refund -- You will get the full dust value for those cards
without the need to disenchant them, up to the maximum number of copies allowed in a deck. If you have a golden Ragnaros and a normal Ragnaros, the golden copy will be the one refunded. So basically there is no drawback to getting a gold version of those cards now.
No more adventures -- There will be three full expansions per year, each with 130 cards. From the second expansion onwards, they will also make free single-player missions available. Adventures are harder to design and make less money, so I guess I can understand why they did this.
More Wild support -- If you care.
New Rogue hero -- Quest reward for winning a number of games.
Other things -- There will be limited-time daily login rewards which go from gold to packs.
All of those look like good changes overall, the only mixed bag for me is the Adventure one since it introduces more variety at the cost of making the game more expensive. I might just begin to play again, though definitely going to try doing more Wild.