An honest review from a decade old fan: If you have NEVER played a Pokemon game before, you might enjoy yourself. But I worry you will not understand what made these games so special and why Pokemon became a household name. To understand why these games are so magical, you need to go back to the handheld consoles and have a crack at games like "Emerald", "Platinum", and "Heartgold"/"Soulsilver".
Many of the flaws with the games have to do with how the developers blatantly ignored longtime fans and made decisions which would cause any other game developer their entire fanbase and credibility. It is grossly apparent that these games were rushed to development. But again, if these are your first steps into the world of Pokemon, you will have a fairly decent time. However, I wouldn't be surprised if you walked away thinking "Huh, not sure what the hype was all about".
Instead of Sword and Shield I have other recommendations based on what you want to get out of Pokemon:
Light Story, Heavy Gameplay: Heartgold & Soulsilver
Heavy Story: Black & White, Black 2 & White 2
A Good Challenge: Platinum
What makes these games even more appealing is the cost. For the full Sword and Shield Experience you need to hand over $90 per game. A quick google on my personal favorite, Pokemon Platinum shows that you can pick up the game for $20-$40 bucks.