Apologies to start - I am not an ATPL. I haven't read all this thread but there seems to be little reference to the Captain's experience as a glider pilot / instructor, reported (from FAA records) on the NY Times website and elsewhere.
Whilst of course a professional ATPL would have the training and procedures for a ditching, maybe that added experience of flying 'sans moteur' helped him to be less fazed? Most (private) power pilots I know think it a real challenge if the fan stops. We glider pilots consider there is less to go wrong without an engine!
But maybe the Captain drew on his gliding experience, not least in having an intuitive sense of the glide slope enabling him to assess rapidly his options, the hold off at the right speed etc. And particularly keeping wings absolutely level without loooking at the panel (what was left working!). Interesting, the Gimli episode pilot was also a glider pilot, as was the guy who got to the Azores (? I think) when out of fuel en route from Canada, spotting a dead stick landing at an island military base after a glide from some 35,000 ft or so over the Atlantic
Just my penniesworth.
Oh, and I hear the CAA is considering compulsoary gliding courses for ATPLs. Should solve the recession problem for gliding clubs.
Anyway, as others say, brilliant piloting.