Currently in Tokyo from UK, paid for an Airalo esim before I arrived, and I was pretty impressed with how cheap and easy it's been- and that's with 20gbs data, which I've barely used.
My service provider O2 would have charged me £7 a day with their O2 travel bolt-on, but would have still been my usual contract of unlimited calls, texts and data, just that the data would have been throttled a fair bit. This is a lot more reasonable than it used to be, but still would have amounted in a large bill compared to the one off $18 esim.