Specific thoughts:
Rainbow Rocket: Pretty pleased with what I've seen so far! I honestly thought it was unlikely that other team leaders would partner up with Giovanni... I truly do wonder if there's more going on than what we're seeing, here?
Also, really interesting that Giovanni has a Mewtwo! I'm going to make a reasonable assumption that this is all post-game material, and as such all of the evil team leaders are going to be slightly under Giovanni's level. So probably 70+, while Giovanni himself might be 75+. That would, at the very least, provide a decent enough challenge worthy of a decent post-game.
Battle Agency - Battle Factory was definitely one of the more interesting facilities in the old battle frontier, so it's nice to see Game Freak doesn't disappoint by leaving the Battle Tree as the only post-game facility in the area. I'm personally looking forward to what kind of fun the Battle Agency is going to provide!
Legendaries all making a comeback - about fuckin time. I originally had my doubts because we could just Pokebank legendaries off of ORAS, but it seems like that won't be necessary, now. I was most looking forward to the legendary birds appearing again and I got what I've been waiting for, so I'm a happy camper!
Overall, this has been an amazing news reveal! Already looking forward to what TPC/TPCi have in store for us next Friday. :o