First, you certainly remember the review I made of the R version of this 3rd generation: www.watchprosite.com
I think it is a fantastic watch, technically speaking, the new in-house movement is much more than a in-house adaptation of a Lemania or other existing caliber. This is a real and guenuine Patek movement (I'll make a post about the 29-535 soon).
This caliber thing is why I prefer the 5270 compared to a 5970, even if I love the refinement and beauty of the latter. Depends on what we are looking for.
On the aesthetical side, the 5270 is more modern in the good way: it gathers the classical look, very traditional in the spitirit but with a contemporary touch that brings it in the new era without altering Patek's DNA.
And I love tachy scales: on this last generation, they are back and I like that (on the other hand, some people might prefer cleaner dial).
I also wrote in the past that the winding feeling is fantastic and that the pushers' softeness+sharpness is the best I could experience (last one was the Datograph which I feel now is a little too soft, to my own taste of course).
I don't see an objective negative element.
I'll post some pictures in the future too.
Cheers, Mark