One of the main things to come out of the trailer for me is the indication that Rand and Egwene are already physically intimate. Changes that dynamic completely(but could have very interesting impacts on their story/conflict as it progresses) but was probably necessary for a TV audience in the wake of ASOIAF. WOT has some exceedingly dark moments but its approach to sex was closer to LOTR than GOT, and it is apparent how the tone matures over the series.
Liking the castings for Mat and Perrin.
I don't see it being a smash hit, something like Game of Thrones always had the historical drama/Political infighting aspect along with the grittiness to pull in the casual viewer before the fantastical elements could put them off.
It probably won't be GoT, I agree, though it might help that GoT failed so badly at the end. At least WoT is complete, and the big problem isn't that they have to make up stuff but rather all the stuff they have to cut.
As far as the political stuff, we'll get some of that later, when Rand starts ruling nations (and Elayne too, just hopefully with fewer baths). A little bit this season too, by the looks of it, with the Aes Sedai stuff (Siuan is in). If the show ever gets that far, I think the whole White Tower politics angle could work quite well. Even has some "shocking" moments in there, such as when Siuan is deposed and stilled. I reckon they'll build her up a bit more early on than in the books, and make her the same badass she was in the books, so that the audience likes her.
The relationship stuff, yeah definitely. I think they'll play up the relationship between Rand and Egwene, so that when they have to separate it's a bit more complicated than two shy teenagers.
I just hope it sticks around if it's good, and doesn't if it's not. Really hoping Amazon don't ditch it because LotR becomes more of a success (which is likely, but not certain). Though they've had to have planned running them together. Even though WoT was delayed a year, they've had to have known they couldn't do the show in less than half a dozen seasons, presumably.