I thought pretty much what most people seem to have thought; it wasn't a great teaser, but I'm still hopeful. It started off fine (I don't mind the kid at the beginning at all) but towards the end when it should have been building up to some sort of cool money shot it just sort of stopped, as if the editor forget he was making a trailer and not a TV spot. But there was still some cool stuff in it.
I loved the shot of the Predator jumping down into the back of the truck and wreaking havoc, even if it was with the poor man's 'way less practical' smart disc (I've never liked the shurikens).
That's just the sort of thing I've always wanted to see more of in these films, the Predators being a bit more agile and mobile. The ship looks new but has clearly taken some inspiration as far as the general shape of it goes from the P1 scout ship, so that's nice. And the new mask looks fine. It's certainly a distinctive new design. It's not my favourite mask to date, but I don't dislike it either, so no problems there.
I also like the idea of the military/government crossing paths with the Predators on a bigger scale than we saw in Predator 2, so I'm digging that aspect of it. I'm not really a fan of the "upgrading/hybridisation" angle, but so long as they don't try to retcon all the previous films and instead make it clear that it's just something that certain Predators, or a certain tribe/clan etc. go in for then that's ok. One of the things I liked about Predators was it basically had its cake and ate it too. It introduced the Super Predators that had a different look and used different gear and hunting tactics, but they had Classic in there too to make it clear they weren't trying to overwrite any of the stuff that had come before.
I've stayed far away from the leaked script so the only spoilery details I know of it are the ones some people keep mentioning out in the open so I'm not going to go searching for confirmation of any of that stuff one way or another. Certainly some of the things I'd heard, which have now been confirmed in the teaser and official synopsis, gave me cause for concern. But fingers crossed! Just as long as they don't go and release an R-rated trailer like AVP:R and Alien Covenant did in an attempt to say "hey, look! This one's got gore!"
That would certainly not be a great sign.