Hardware-wise, it's pretty great.
Aside from the dual aperture, the biggest change for me is the sensor itself. Aside from the improved autofocus, the other big change is the stacked DRAM on the sensor itself. Samsung is by no means the first to do this (Sony was) but they may be able to kick start a trend. Google may probably use this to their advantage to further improve HDR+.
Of course, good hardware is only part of a great camera. Software has to play a role too. Samsung is touting image stacking as part of their efforts to reduce noise but it's interesting to see how it stacks up to HDR+, arguably the best form of automatic post processing out there