Well, completed insofar as the story is done. Actually, there are four stories – three “paths” to take, then a final story available once you’ve done all those.
As with other recent Pokémon games, getting to the “end”, beating the Elite Four, then completing the story and defeating the final “boss” was all very, very easy. Yes, you need suitable Pokémon for each part, and yes, they need to be sufficiently levelled, but I was totally overpowered by the time I’d done 5 or 6 gyms and was a laughable 15 levels higher than every opponent for the rest of the game.
With that done, though, I realised that I was closer to completing my Pokédex than I’d ever been in any other mainstream game in the series, so I think, for the first time (Arceus doesn’t count!) I might actually try to catch ’em all. I’ve about 50 left at the moment, with around half (I think) easily obtainable from just evolving other Pokémon I have already, and most of the rest available from my daughter’s copy of Violet.