Not worth it at the moment.
I was in talks with some of there engineers, and basically 4.4 was going to be Android 5.0 but they had major setbacks (something along the lines of meeting under-the-hood requirements with visual effects, i dunno).

Anyways the vision for future Android seems to be:
-A new name and number (Android 5.0 Lollipop ?)
-(one of) the latest Linux kernels (3.9)
-Merging elements of the Android and Linux kernel (single branch)
-gcc 4.8
-64-bit support
-ART*
-support for real MultiTasking (no for phones, maybe for phablets, in-discussion for tablets)

The version that runs ART is (certainly) likely to be changed. So those people porting Apps... will have to do it again. Why do you think the crazy popular Xposed Module Framework hasn't been ported? They were discussing making a leap (which I think is best), but instead they're looking for iterations of these things.

So we might get the new ART and 64-bit suppot in the next revision, and maybe gcc 4.7. Then we'll get gcc 4.8 and the new kernel after that. Then we'll get a minor iteration where these things play better together, and play better in the OS and SDK. And then we'll probably get a user inter-facelift and Multitasking for (large) devices.

Then gradually we'll see this evolve more and more, especially when it comes to integrating everything with Google's services. And integration regarding Phones, Tablets, Notebooks, TV's, Consoles, Cars, Wearables. Its a weird strategy but Google's too much of a behemoth for them to fail.

I'm not sure if this meets the criteria of latest and greatest but I find it fascinating that Samsung actually changed an OS from Android to Tizen via a update! (manual at this point) Is this unprecedented?

http://www.engadget.com/2014/05/30/s...android-tizen/

Latest and ...biggest!

http://www.androidcentral.com/samsun...7-inch-display

7 inch screen phone