On the technical side, the ARM chip has much to recommend it to the programmer. The whole point of a RISC architecture was to produce an instruction set, all of whose members execute in one clock cycle. Which in turn makes the instruction set fast. Though this is usually achieved at the expense of the convenience of complex addressing modes found on processors such as the Motorola 68000 family (which performed sterling service in Atari STs and Amigas in the 1990).
The original designers of the ARM included some neat tricks to get around this problem. First, they made every instruction in the instruction set capable of conditional execution, which meant that you could eliminate branch instructions and speed things up enormously if you took suitably sophisticated advantage of this feature. Second, they included a barrel shifter as part of the CPU hardware, and made its tricks available by allowing shifts and rotates to be performed simultaneously with other instructions, again adding to the speed of the CPU.
For those used to the instruction set of, say, an Intel 80x06 type CPU, the instruction set takes some getting used to. But once you have acquired familiarity with the ARM way of doing things, you can write code that runs at ridiculous speeds. When the ARM was first offered to the public, back in the early 1990s, via the Acorn Archimedes desktop computer, it blew other CPUs out of the water with its blisteringly fast execution, and that was at a time when the CPU was clocked at a measly 8 MHz clock speed. Modern ARMs are clocked at 480 MHz and beyond, and at 480 MHz, well-written ARM code will outperform Intel x86 code on a 2 GHz chip.
One early problem that surfaced in the 1990s, was that compiler writers were caught on the hop by the unique nature of the ARM instruction set, and it took time for properly constructed optimising compilers for C or C++ to emerge for the ARM architecture. That hurdle is now overcome, of course, and the software developement around the ARM architecture is now mature and solid - boosted by the fact that the ARM was the go-to processor for many tablets and mobile phones even before Apple got in on the game.
Another nice feature of the ARM architecture, is that it's one of the more open architectures in existence. Over time, the ARM instruction set has had some nice extensions added to it, such as Jazelle, for direct execution of Java bytecodes, and more recently, extesions facilitating the speeding up of JavaScript in browsers (and by exension, speeding up of the node.js runtime).
As an example of what the ARM is capable of, take a peek at this: a "neo-retro" computer called the Maximite 2, that runs BASIC, but which achieves execution speeds in BASIC that were only achievable in assembly language just 20 years ago:
However, now that I've covered the good stuff, it's time to look at the not to good stuff. Almost all of which centres upon Apple's well-deserved reputation for egregious abuse of monopoly power. Those old enough to remember Microsoft's obsession with vertical control and vendor lock-in in the 1990s, will recognise the territory in question immediately, but Apple has taken this, in some areas, up to Spinal Tap 11. An independent computer servicing shop that has had numerous run-ins with Apple is this one:
and he has an entire series of videos covering the requisite issues, including abuse of monopoly position for the purpose of egregious price gouging. Indeed, so pernicious has been Apple's pursuit of vertical control, that its activities spawned a "right to repair" movement in the USA. Though, in the interests of fairness, the above individual also notes how Apple ended up being the good guy in a spat with Farcebook's Mark Zuckerberg, who claimed (falsely) that Apple's promise to deliver enhanced privacy protection on its devices in future would be "anticompetitive" and "harm Facebook's business". Well, if your business is data-raping Farcebook users and selling their data to the highest bidders with no scruples at all, perhaps it deserves to be harmed ... but I digress.
Part of the problem here is that the days of Apple being the rebel alternative to the Microsoft empire (to break out the overworn and clichéd analogy that might have held in the early 1990s) are long gone. Apple has now become the replacement $2 trillion corporate empire, the financial Imperial Star Destroyer that even some banks tread in fear of. And it's acting true to type. Which might lead to some friction with the people at ARM if they trying being too proprietary with the CPU architecture, which wasn't Apple's intellectual property to begin with.
Another part of the problem, is that Apple attracted a fan base, back in the days when it was the rebel alternative to the Microsoft empire, by providing original and technically challenging solutions to certain niche problems that actually worked at the time. Back in the 1990s, Apple hardware made Adobe PhotoShop possible, and Adobe had to bust a gut to deliver similar results on Windows platforms in the days of 75 MHz Pentiums. But now that even cheap laptops can feature a dual core Intel CPU running at 2.4 GHz, the list of tasks that are beyond the reach of such machines in reasonable time has dwindled accordingly. The sort of tasks requiring ingenious solutions to be manageable on a laptop, are now in the realm of high end research conducted by teams with budgets allowing them to book supercomputer time (or in some cases, buy their own supercomputer exclusively for the purpose), but occasionally, one sees episodes of brilliance such as this, which may even bring the dreaded Navier-Stokes Equations within laptop reach in the future.
So, in summary:
[1] The ARM CPU architecture was a stroke of genius when it first appeared, and is still a force to be reckoned with by those in the know, even if it didn't have the same mountains of cash thrown at it as Intel's x86;
[2] Apple choosing ARM for laptops may be the endorsement the architecture finally needs to supplant x86;
[3] But Apple has a less than happy history with respect to corporate practice, which could spoil the mix badly.
However, if Apple delivers on the privacy front on its devices, and succeeds in wiping the smirk off Zuckerberg's face (see more on this in the following video clip):
then I'll be happy to cheer Apple on in this matter. But I won't cheer them on if they leverage the ARM for more price gouging.