Most of them just give impressions of what we have seen before, in teasers and trailers (Bran's Tower of Joy flashback, Daenerys arriving at Vaes Dothrak, Arya training with the Waif in the House of Black and White), or what can plainly be expected (Tyrion thoughtful after his encounter with the dragons, Davos surprised when finding Jon alive).
BUT there is one new picture that caught us by surprise: Qyburn in his laboratory, talking to or listening to a bunch of kids in shabby clothes.
And alas, we have seen those kids before, in a very short scene of the first trailer:
They seem to be hitting or stabbing a person on the ground we are not shown. Book readers were reminded instantly of the epilogue of "A Dance With Dragons", where a group of kids stab Kevan Lannister to death. Watching this scene is Varys who just a moment before had killed Maester Pycelle. These two killings were part of Varys' plan to destroy an upcoming alliance between Lannisters and Tyrells, promoted by Kevan Lannister.
So, for the show, there could be two possible explanations for those scenes:
1. The kids are indeed Varys' "little birds" and they kill Qyburn. This would be contrary to Varys' plan in the books, as it would weaken Cersei and strengthen her opponents in the council, Kevan Lannister and Pycelle.
- We know Varys is looking for the strong man behind the Harpies, and he will be leaving Meereen - this could go along with him being behind the killing(s).
2. The kids are Qyburn's little birds, and they kill Master Pycelle. This would be close to the books' plotline, only the roles of Varys and Qyburn as master behind the killing(s) would be switched, but with the same result.
- Cersei definitively wants to get rid of Kevan and Pycelle, who used her imprisonment to strengthen their own positions. Qyburn told her in S05E08 that "Grand Maester Pycelle has summoned your Uncle Kevan back from Casterly Rock to serve as Hand of the King. He now presides over the small council."
- Even before her imprisonment, Cersei gave a hint about her feelings and plans regarding the Small Council. After Kevan taking his leave towards Casterly Rock in S05E02 and Mace Tyrell being sent to Braavos in S05E04, Pycelle comments that "the small council grows smaller and smaller", to which Cersei answers: "Not small enough."
- In the episode 3 preview we hear her giving an order to Qyburn, in the presence of Jaime and the FrankenMountain: "If someone is planning on making our losses their gains, I want to hear it." This could imply that Qyburn obeys by sending out his little birds to spy on Cersei's opponents, namely Kevan and Pycelle.
- Finally, there had been a report about a scene with Qyburn, Pycelle and some children taking place under Shane’s Castle, where Qyburn’s Laboratory is located.
Besides all that, I'm very curious to see how Jaime will react when being introduced to Cersei's new creepy counselor and having his first meeting with the undead King's Guard, the FrankenMountain. I highly doubt this will strengthen his relationship with Cersei...