While I haven’t really needed BLIS much driving round, it is useful as a supplement I find. I believe that it also includes cross traffic detection when reversing out of a space, I’ve found that very useful to warn of approaching cars and people if a van has parked next to me.
With ACC it can slow you right down and speed you up all without any input from your feet. If you’re in stop start traffic, or just very busy roads and no one can drive at a constant speed then it helps. It’s about taking the stress out of driving. I use it all the time on dual carriageways and it really does help. Tried it once on a B road, never again!!
Also of great use in an average speed camera zone as you’ll know you won’t go above the limit and thus can keep your eyes on the road much more and less glancing at the speedo, useful in contra flows and narrowed lanes in roadworks.