IMO, smartphones had the chance to revolutionize the gaming industry, but ended up wasting almost all of that potential on skinner boxes riddled with ads and microtransactions. Most of the best mobile games are ports from other systems, like the mobile edition of Minecraft and whatnot.
I think Pokémon Go was possibly the closest any major publisher has come to actually realizing the full potential of mobile games as a format, but it still fell painfully short with massively dumbed down mechanics and an absolute grindfest of a progression system.
There are still a few good indie projects out there (I like Soul Knight) but generally the mobile gaming market is so full of absolute dreck that I usually just don't bother.