Speaking of the A8X. Here's a reminder from last year.
http://www.anandtech.com/show/8716/apple-a8xs-gpu-gxa6850-even-better-than-i-thought
So Apple claims a 2X performance increase from that. I didn't get last years iPad Air 2(or the year before it), but there are several things going through my mind:
1. Does Apple need this? The only logical conclusion I have is if they are going with a 4K display, but Apple has often been good at ignoring fads. Look at their core count. Apple completely sidestepped the MOAR CORES hypetrain and with good reason. Do people really need 4K at 10-13 inches? So if not 4K, why would they need this massive GPU increase? They talked vaguely about how this will "unlock new applications" but from what I saw being demoed, I doubt that you couldn't do that with an A8X quite well.
It's 5.6 Megapixels for the MaxiPad and I'd say that resolution is most definitely needed. The pixel density happens to be exactly same as the iPad Air 2, at 264 ppi, which is Retina. If it went much lower, it would lose its "Retina-ness" IMO. The Retina MacBooks are lower ppi, but in general laptops are used with a further working distance.
Now given that the MaxiPad can be used like a laptop, some could argue that the working distance might be extended for a lot of people so a lower resolution would be OK, and while that's true, there's bound to be a lot of people who would still use it like they would an iPad Air 2. So, Apple needed to keep the PPI up on this.
So while not 4K it's still pretty high, and add in gaming and you get the need for such a fast GPU.
BTW, the PPI on an Apple iPhone is actually much higher, and that's also needed, because people typically hold their phones closer than they do their tablets.
I actually care more about this (to a certain extent) than the SoC specs. Yeah we knew the MaxiPad's CPU/GPU was going to be fast, but since I'm not an avid gamer and won't be doing content creation on my tablet either, I was more interested in other things, such as RAM. RAM is of ultimate importance for longevity of an iDevice, and it's nice to see they didn't do what I was predicting, which was limit it to 2 GB and then upgrade it next year or so to 4 GB.
Apple has a long history of being very stingy with RAM, and the iDevices suffered this in spades. Apple compensated by being extremely aggressive with memory management in iOS, but it was still an issue. However, it seems that 2015 is the year when targeted a decent baseline. All the main iDevices are at least 2 GB now, or at least I'm predicting they are:
iPad Pro: Known to be 4 GB RAM and A9X
iPad Air 2: Known to be 2 GB RAM and A8X
iPad mini 4: Likely 2 GB RAM and known to be A8
iPhone 6s: Likely 2 GB RAM and A9
iPhone 6s+: Likely 2 GB RAM and A9
Apple TV: Known to be 2 GB RAM and A8
The only outlier here is the new iPod touch with 1 GB RAM, but that came out months ago, and has always been considered a 2nd tier device in Apple's product line in terms of specs, which makes sense given its lower cost.