The rest is mostly gimmicks. I have a Petzl Reactic+, which is an excellent head torch (that seems to have become ludicrously expensive), but the headline features of a beam that reacts to what you're looking at and bluetooth programmability are about 80% marketing guff.
I'm glad you said that - I was just looking at the Reactic and thinking WTF?
The other good thing about the reactive beam is that if you look at someone wearing a head torch, it responds to their beam and turns the brightness down so you don't blind them too badly. Not sure how two reactive torches play together in that respect - presumably they find a happy medium. But it also means you need to use non-reactive mode when there's oncoming traffic (cycling or on foot), otherwise headlights can turn your beam down.
Mostly it's useful when you've got mucky hands and don't want to touch the buttons, though.
The Bluetooth thing... well, it's got a microcontroller so why not, I suppose (the predecessor 'Core' had similar functionality over a USB connection, which was a bit less ridiculous) . There's a mode where you can control the brightness in realtime from the app, which might be handy in a big tent if you've hung it from something and want to control it without leaving your sleeping bag. Except that it doesn't actually let you turn it all the way off.
The one time I actually bothered to re-program the Core was to give it super-low brightness for reading documents when I was attending a film festival (I promptly forgot about this and tried to ride through the Netherton Tunnel the following week - Fail). The Reactic lets you define multiple modes, so I can't really see many cases where you'd want to re-program it, once you've set up a sequence that you like.
They're obviously desperate to come up with features that help sell their product, in a market where anyone can stick CREE's latest between some optics and a battery for awesome brightness. Build quality alone is hard to compete on, and different beam shapes and colours have been done
[1]. So you end up with this sort of marginally-useful rubbish.
True, this is one of the few flaws I've found with my Tikka - good at illuminating handlebars, but you have to crane your neck to shine it on road signs.
Exactly that. Possibly not so bad if you're mounting it on a helmet?
It's okay on a mountain bike or recumbent.
[1] A red beam that preserves your night vision and uses hardly any battery is worth having for camping. Other colours are gimmicks.