So far we've had a pretty great sounding expansion from the Witcher 3, Hearts of Stone, which I haven't been able to buy yet (And it comes with real life GWENT CARDS) but we've also had the announcement of a new expansion, Blood and Wine. I started this discussion for a couple questions.
Hearts of Stone were really awesome, it felt like it was part of the main game, still on the map, which Blood and Wine won´t be.
Blood and Wine should come out in 2016, January-June. Developers said that it will be much larger than HoF. BaW should have 20 hours of gameplay, HoF had 10 (it was actually more, but who am I to criticize official statements from CD Red?)
It should be in land untouched by war, in Touissant, so I guess we´ll get completely new map - which we didn´t get in HoF, only expanded one.
Now, back to HoF. Only thing that bothers me is that HoF gives you a lot of endgame equipment (which is really cool) but you won´t have anyone strong enough to test it on. If you start New Game + you will trade that equipment by the time you get out of White Orchard (I actually traded it off after I completed Bloody Baron questline). So I wouldn´t mind if the HoF was for lower levels, not end game 34. Same with Blood and Wine.