Oh thank god that the old guy with the Hobbits turned out to be Gandalf after all. It's still on the nose that Hobbits were the first ones to meet him and help him a long, but not quite as much as it would have been if he had been Sauron.And it does establishes his interest in and bond with Hobbits.
As for Halbrand. Well it makes sense and I thought the actor did a good chop with shifting from Halbrand to Sauron. I also thought him tempting Galadriel (and using part of the words she would later say during her last temptation when Fordo offers her the ring in Lorien) was very well done, and made a lot of sense.
In book canon Galadriel is called the "greatest of the women among the Eldar" (I assume Tolkien meant the Eldar who actually went to Aman, because otherwise you could pose an easy counter-argument with Luthien) so if Sauron had managed to get her to his side, he would have had someone who's powerful, but not powerful enough to challenge him, and someone who could have brought at least some the Elves to his side without a fight. Since Sauron is a Maia it would make sense that he'd look for powerful Elves to become his commanders, close servants, vassals etc., since other Maiar are both in short supply and, theoretically, could rise to challenge him.
As for the designs of the rings; that's actually how I imagined them to look when I read the books. I thought, while pretty, Nenya was a bit over-designed in the movies, with the silver flower being put above the diamond gem, the most prominent feature of one of the Elven Rings should be their gem, after all.
What I'm a bit confused about is where the Seven and the Nine are supposed to come from in this version? Is Celebrimbor just going to make them now? In book canon all 19 Rings were originally supposed to be used by Elves, the famous poem (Three for the Elven Kings, under the sky etc.) was only made up later after Sauron had managed to seize the Seven and the Nine and gave them to Dwarves and Humans.