Thoughts:
1. I like the vibe of this trailer, and I like how they tie the two franchises (X-men of the present, X-men of the past) together.
2. Um...didn't Dark Phoenix basically disintegrate Prof. X in the last film? How exactly is he back? I know there was the thing where the guy in the hospital woke up, but are we to believe that he magically turned INTO Prof. X instead of simply being the same mind in a different body? Or are we simply ignoring the events of X-men 3 (which, for the record, I'm fine with)? Hey, maybe this film will totally retcon X-men 1-3. Again, I'd be ok with that, even though I enjoyed the first two.
3. I far prefer Singer's work to Brett Ratner's work. The one thing Singer got about the X-men is the sense of being an outsider, which translates well to the X-men. He's a talented director, but I think he's also been hampered by weak scripts. I still very much enjoy the first two X-men films, though.