After a few hours with 4.4.1, I am guessing that the major changes are "under the hood". Honestly the reported fixes for exchange, may benefit anyone who uses the native Android email app, but for true corporate level support, which is a requirement for me, I cannot understand anyone using it for Exchange email. Camera improvements appeared to benefit the Nexus 5 Phone, but then who (IMHO) uses a tablet to take pictures, if you have a decent phone? Battery life improvement is on my "wait and see list." ART for runtime has apparently been given some fixes, but I will reserve ART exploration until I have digested 4.4.1 using the standard Dalvik runtime. Chromecast mirroring is another "wait and see", but it apparently will be Google controlled. Read what Koush has to say about mirroring
Here. I am waiting on the Google change log and will then determine if Google has delivered or not. Right now, I don't see any need to keep clicking the check for update option, as it should arrive over the next few days, unless you are like me and feel the need for latest.