A couple of things from around the web:
The main disadvantage of 64-bit architectures is that, relative to 32-bit architectures, the same data occupies more space in memory (due to longer pointers and possibly other types, and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache utilization.
Why do you see 64-bit as helping performance?
In general, 64-bit applications run slightly slower than 32-bit versions of the same program because the pointer sizes are twice as big, and this can impact cache utilization and increase code space.
Doing 64-bit ALI and FPU calculations does not require a 64-bit address space, and this can result in faster computations, but does not require a 64-bit OS.
The only real benefit of 64-bit is to run natively without complex paging schemes when virtual address space is larger than 32-bit.
But, if you're paging on a mobile device, you are generally doing something wrong already.
...and then of course there's fragmentation.
I'm not saying it's a bad thing, just saying the transition doesn't seem necessary at this point. Which is what makes me think it could be more about Apple gearing up for ARM on the desktop.
As for the ungroundbreaking stuff, it's pretty much the same chassis as the last four years, the same screen as last year. As for the camera we'll have to see what the reviews say. I'm not sure it can be classified as a gamechanger. The fingerprint thing seems a bit of a gimmick designed to work around the patents Google must hold for the innovations they've made in that area with pattern unlock, facial recognition unlock.
Overall I don't think it's a bad update, it's just an underwhelming one, which everything more or less has been since the 4.
