When Apple announced the iPhone 5S one of the new features was that the new processor (the Apple A7) had jumped from a 32-bit to a 64-bit architecture. There are a few reasons why having a 64-bit processor is better than having a 32-bit processor and an awful lot of myths and half-truths out there! Google announced in June that Android L would also have support for 64-bit processors and to an outsider, it appears that Android is behind iOS in this respect. Maybe it is, maybe it isn't but I'm of the opinion that at this time and space, it really doesn't matter.
The number of bits that your processor can handle is relevant to only some aspects of how you use your device. For the desktop environment, one clear benefit of a 64-bit processor compared with a 32-bit processor is the amount of memory that may be addressed. This isn't simply the amount of RAM that the processor can access (32-bit processors are limited to 4 GB of accessible memory, 64-bit processors are not) but about how quickly that memory can be addressed. It's less relevant for our Android devices to have 16 GB of RAM and more relevant for those ultra high resolution displays (similar to the Nexus 10 and beyond) that companies insist on placing in their high end devices.
The speed of memory access is important but so too is how quickly our processors can execute instructions to run code. This is where we run into the race for idle scenario: if one processor can complete a command and return to an idle state quicker than the next, it tends to use less power. Of course, things are more complicated than this simple example but the point is that modern processors are quicker and more efficient at the same time. This is thanks to an evolution of the current instruction set, called ARMv7 and set to move into ARMv8. Marketing departments believe that the headline “64-bit is better than 32-bit” is an easier sell than “ARMv8 is better than ARMv7.” I'm guilty of it too; look at the title of this article.
Where does this leave us from a productivity perspective? In the short term we're back looking at battery life. We want to be able to to as much as possible with our mobile device using as little as possible and all refinements to existing technology is gratefully received.
Things are more exciting in the longer term. We may reach the point whereby the device in our pocket is used to drive a large, high resolution monitor, wireless keyboard and mouse and deal with desktop-grade applications. Perhaps we won't need a desktop computer any more because our mobile device will fill that role (we'll still need monitors, keyboards, mice). If we reach this point of computer evolution, we're going to need desktop class processors with mobile class power consumption. We already have the components required for this: high performance 64-bit mobile processors are about to be installed into Android devices, Chromecast makes it easy to send information on our device to a big screen, Bluetooth allows concurrent connectivity with mice, keyboards and headsets. We are close.