I’m not entirely convinced it’s all down to poor performance from Ring. My phone “rings” almost instantly, especially when I’m connected to the same wifi, and yet my wife’s phone, connected to the same wifi, has large delays.
As for when I’m out and about, with a good 4G/3G signal it works well but less so depending where I am. You have to take signal coverage into consideration.
That said, marketing must take some flak as they make it sound like it’s always going to be instantaneous, which is unlikely given the number of variables.
Just my 2p/2c 
Tony