In my opinion, yes. I've played Legends Arceus for longer than I have Sword, and I might even go so far as to say it's my favourite Pokemon game from the past decade, narrowly beating New Snap and the Ruby/Sapphire remakes.
The game isn't as battle orientated, and has more focus on catching Pokemon and 'studying' them. The battles you do have are arguably harder than they are in the main games, and a few times you'll be battling 3 against 1. Since you can see them on the map, hunting for shinies is made a lot easier, too - I already have 2 full boxes of shinies, and I only shiny hunted four of them! You also don't need any other game for 100% completion, since every Pokedex Pokemon can be caught in this game. There's a lot of end game content, although it might get a bit repetitive after a while.
I have Brilliant Diamond, and I've pretty much stopped playing now. It's filled with bugs, and I'm not sure how many of them were fixed in the end. Leveling up takes forever, at least by today's Pokemon game standards. Logging in each day just to see what the two daily Pokemon are gets boring real quick when you receive the same ones over and over again. The secret bases now consist solely of Pokemon statues in bland poses. For me, the game serves as a quick way for me to dump excess Pokemon from Sword, Arceus and Home in the boxes. I'll admit, as a huge fan of the D/P/P games, this one was a disappointment.
