Grin coin has definitely had interesting journey since it was launched earlier this year. Development work is still ongoing and they have just had their first network upgrade via a hard fork successfully with no issues.
While it is still difficult to use, hopefully it can deliver true digital cash.

We also did a coverage on it in our Q1 report when Grin was launched https://assets.coingecko.com/reports/2019-Q1-Report/CoinGecko-2019-Q1-Report.pdf