I use a referenced catalog and the number of images in it are increasing and will do so even more next year as I intend to gradually import all my previous Lightroom catalog images. ( 2009 to 2014 )
Consequently filtering on All Images is becoming more frequent so the speed improvement in " loading " all the images is most welcome.
LAB readouts .... finding the a & b values ( -a green, +b yellow for example ) useful for assessing colour casts then making a judgement on whether it needs correcting, which is where the new masks / layers features will be put to good use.
Personally, Annotations & Crop as a path are not things I would use but Phase One has to add features for the Professional ( Phase One Camera ) photographers so I am OK with that
There will probably a few more things that I find useful once David Grover, of Phase One, has done some v 11 webinars and I have had a chance to attend / watch them