So I've had a good go at different tasks now, so can comment a bit more constructively.
Safari
What a difference 2gb of RAM has made here. You can switch back and forth from various apps to Safari, and no reloading, even with multiple tabs. Smooth to say the least.
Screen
A great improvement - not that there was much wrong in the first place (I moved from Retina Mini). This is a dream for me as a hobbyist photographer. There simply isn't a better tablet screen anywhere else. It will also be even better than before for showing photos. Next step for iPad can only be to 4K - my tiny mind can't fathom how they could possibly improve the clarity of the picture any further! I've no concerns with yellowing/distortion etc (to date any way!)
Audio Playback
Here comes a slight negative for me - music playback, there is quite a bit of vibration in the device, both on screen side and back, when playing music - starting at around 50% volume level. No distortion to sound itself, but a touch irritating to hold the device or place in your lap when listening to audio. I played a bit of Republique, and you can literally feel the footsteps by the guards in one scene. Unintentional haptic feedback? I guess it's the price of thinness - not sure I heard many reports of this with last year's Air though? I've certainly noticed the difference between the iPad Mini and Air 2 in this respect.
Gaming
As good as you'd expect. Smooth, fast, graphics slightly improved over the Mini Retina, but then again, this was in playing games nearly a year old. There must be potential for more apps to unlock the graphical capabilities (I'm not much of an iPad gamer so can't test any recent games to be honest). I tested Republique, can't say I noticed any exceptional difference in this device compared to last years.
Still to test cameras - I think we know where we stand with those though!
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I concur! Only slight negative is the 'feel' of audio through the device. No sound distortion, but definite vibration around the speakers on front and back of the device. Have you noticed this?