I don't have one.
I'll say that up front so you can just skip down to, hopefully, a response from someone who has one.
I've looked at the
photo and read
the instructions and combined with my (non-Kawasaki )
large tank bag experience I've been embolden to respond.
I don't think you will have any trouble seeing your phone. My large tank bag experience says the only problem you may have is inadvertently honking the horn during full left lock maneuvering.
I use a gas ring mount, so when refueling I always dismount the bike and pull the cord release and set the bag on the seat. It appears that if you normally refuel while sitting astride the bike that
the Kawasaki bag (as would mine) will be problematic. If you have no problem with a dismount to refuel, then it appears that you would need to pull up on the rear to release the hook and loop and then either; remove the front straps from the bike's hooks (if the bag is fully packed), or set it aside the gas cap (still attached to front hooks) if it is lightly loaded. It does look (to me) that it would be more hassle than a gas cap mount but then it is considerably cheaper than most of those, and if you don't think you'll use it much then it's probably a good option. If, like me, you feel a little naked without a tank bag then I'd spend more and go with a bag that has a gas ring mount. Most of those are ugly when the bag isn't on the bike so that may be another consideration for you.