In my opinion, Photospheres are one of the coolest camera features of Android. I don't use them that often (not often enough, anyway), but I always take some new ones when I go visit my grandparents in Virginia, because the country up there is just too beautiful to ignore. These Photospheres give me something to look at when I'm feeling "homesick" for the place where I grew up.
As time has gone on, the team behind Photospheres has made subtle improvements with each Android version bump, and KitKat is no different. This go they've improved image stitching to find the "ideal place to stitch the individual images together to avoid moving objects, people, or otherwise difficult spots" through a technique called optimal seam finding. This is something that Photospheres has needed for a while, because it's so easy to mess the stitching up because someone walks right through the middle of your shot or you move slightly. Hopefully this will fix that. There have also been changes made to improve Photospheres in "challenging" situations, like indoors.
Photospheres should also render faster in KitKat, as it now uses multi-threading to create the final product.
So, better pictures and less waiting. Sounds good to me.