I'm shocked the magazines and road-tests discuss this feature so appallingly in their reviews. I have lots of experience using in cars, but only tried it on a GS quickly and I think it was the posh setup - but if I ran the place there'd be some software tweaks to make it much more user friendly
two types on the GS, a £500 setup I think is just radar cruise, and £750 radar cruise, blind spot assist, and some rear end crash mitigation stuff.... I've had it on cars for 11 years, so for me there's no learning curve on the weirdness of a vehicle doing its own thing when using radar cruise - I wouldn't own a car without it
on Bikes all the reviews say it backs off too early - and it does - and that's about as much as they bother to say - so here's a bit more info
on cars the closest gap you're allowed to have is the two second rule - which in the rain feels dangerous at first, till you understand it pays more attention than most car drivers and it will cope even this close... With BMW cars, the gap to the vehicle in front defaults to a 4 ish second rule when you first switch it on - so you immediately need to go in menus and change the setting every drive - And once used to it and trust it can manages things, a 2 second rule is best for busy traffic, or effectively you go backwards as everyone will pull in to the big gap it leaves. 3 seconds is best in the rain, so the default is plain wrong from the factory. My Merc allows me to set the gap far more easily, and yet it remembers whatever gap I had for next use anyway - which is light years better than BMWs iffy setup - but its less decisive than BMW system, so I leave the Merc dithering at 3 seconds - where it also works best for stop start traffic - which is something the BMW bike systems doesn't do...
of course on a bike, as it can't stand on the brakes as robustly as a car (in case you're not paying attention or riding one handed, where it may corner, move lanes or just crash) it seems to have a 3 second rule as the closest possible gap. whatever it is, its miles away and quite irritating - so if you normally ride close to the vehicle in front, then nip by, this system will have backed off way beforehand, meaning you don't get close enough to overtake without opening the throttle manually... sensible ? but seems irritating and unnecessary
on a long boring trip when not pressing on I expect you'll be happy you have it - but in rush hour motorway commutes, I suspect it'll be a disaster and almost unusable
and for me likely the most frustrating point - you can't set a speed anyway near as easily as the std cruise bike's can - the old system works great - on my k16 in any gear and any speed - so if I wanted 8 mph in first, it just sets immediately and works perfectly - which is very useful
the Radar system wanted at least 20 mph which is very irritating - and it didn't like to set ! - appearing to want to understand the conditions first then try and fix a speed when it wanted - it was likely faster than it felt, but it seemed like it needed two to three stabs on the button and about two seconds before it would take the instruction and set the flipping speed. Whereas the K16 with std cruise, you tap the button at any point and that's it - set in a millisecond every time !
if you want to set a speed when the gear you are in isn't suitable - it throws a long winded almost confusing message on the screen. "wrong gear" would be far simpler. And its too cautious as well, 20 mph wanted the bike in second gear - where third works more calmly for a steady 20 mph
and another problem - it just gives up below 20 mph, with almost no indication - I'd have expect an audible beep - but it only pops up on the cluster you aren't watching as the traffic has built up - and thus its all down to you...