I’ve had an Active 10 for 6 years, still going strong although it’s been back for a couple of services in that time.
Excellent tool for navigating, especially with 1:25k mapping. 1:50k is not quite so detailed for off-road but not bad, and perfect for road-riding.
As TurnerGuy says, buttons are much better than touch-screen for muddy fingers. The silicon case does make it quite bulky but also pretty much bullet-proof as well as weather-proof.
Plenty of battery power for big rides. If you’re doing multi-day stuff, you can get a spare battery, and also there’s a caddy that lets you use standard AA batteries instead.
I’m not sure the Active 12 is a massive advance on the 10 although it has higher-res maps and some wireless connectivity – wasn’t enough to tempt me to upgrade. And both the 10 and the 12 are pretty much purely navigational tools rather than having any training functionality.
But if that’s what you’re after (and its what I’m after) then it really is a great bit of kit.
An alternative to a new 12, might be buying a second-hand or old stock 10, and spending the difference on 1:25k mapping. The maps are still expensive, but vastly cheaper than they used to since Ordnance Survey’s licencing rates got slashed a couple of years back.