So, now that I've beaten Shining Pearl, I guess I'll give my final(ish) thoughts about it. Before I start, let me just reiterate, I never played the original Diamond/Pearl/Platinum games. I know a lot of people are disappointed that it didn't include more from Platinum, but never having played it, I can't share that context.
Also, one thing I think is important to my views on this is that I came into the whole Pokemon fandom with OR/AS followed up with X/Y. My main views on how those two relate are that they had a lot of the same quality of life perks, same feel with graphics and story...they felt very similar to play only with different characters and geography.
The comparison between BD/SP and Sw/Sh is quite a bit different. Graphics are different, quality of life features are different. Story set up is different. With OR/AS and X/Y feeling so similar and those being the one previous generation I've had experience with to have a generation remake concurrent with the new game (seeing as how Sun/Moon only had the Ultras released in the concurrent generation and that's hardly the same), it was weird to me that this generations concurrent remake would play so vastly different from the main game.
So that's the baggage I'm bringing into this game. Now for the actual review.
Graphics
I honestly didn't mind the chibi graphics while I was playing it. I've played plenty of games with chibi with no problem. But then I just loaded up Shield tonight and it hit me smack in the face just how different it really is. While I don't really find it as a fault with Shining Pearl, if I were in a "choose one to keep and one to never play again," I'd definitely be leaning towards Shield in this respect. Still, graphics aren't everything. So let's move on.
Pokemon Selection
I played a little bit after opening up the National Pokédex. But in full disclosure, I didn't play too much longer as I've kinda grown bored of the grinding I had to do just to beat the champion. My impressions are that BD/SP have some Pokemon that Sword/Shield doesn't have and Sword/Shield have some Pokemon that BD/SP doesn't have. It still comes down to a lot of Pokemon still being held in my Home boxes. This is honestly kind of a wash.
Presentation/Quality of Life
Things Sword/Shield do better: I like that you can see wild Pokemon instead of random encounters. I absolutely did not miss random encounters of the old JRPG's and I really wish BD/SP hadn't thrown back to it. Me, I'll always have the EXP Share on whenever it's offered. I also love the various ways to power level your Pokemon (typically with exp. items that you can get from Max Raid Battles). But the thing that Sword/Shield did right over BD/SP is that they make it optional. Yes I'll always use the Exp. Share if given the option. But I know there's purists out there that (for whatever reason) actually prefer the grind. It shouldn't have been forced. Chairman Rose as the antagonist, okay, I can't defend this idiot. Like, he had a firm hold of the idiot ball and just wouldn't let go. But compared to Team Galactic where you fight a few grunts, infiltrate their (rather simplistic) base and then the leader just up and nopes right out of there the moment you capture the box legendary and you never see him again? Like seriously, where the hell did they go after that? Were they arrested? Did they flee the country? What the heck? Also HP's not breaking when you use them was a nice Quality of Life improvement I'm sorry they took away in BD/SP
Things BD/SP did better: One quality of life thing I liked is that you didn't have to actually capture all of the Pokemon in order to have them in your Pokedex. For one thing, this gave you a way to have the other box Legendary in your dex without actually having to encounter it. Also, I already have several of the Lake Guardian trio in my Shield PC. I just really didn't feel like having to capture all three of them to fill the regional dex so that I could get the nat dex. So I like that they made it easy on you. The Grand Underground is honestly the best kind of "Sidetracked by the Gold Saucer" I've had in a Pokemon game yet. I may continue playing BD/SP for one thing just to fill bits in my Home living dex, but also because the Grand Underground is actually pretty fun.
Final Notes
I am glad that I got Shining Silver. There were little bits that took me back to my days of OR/AS and X/Y. I may even continue playing it for the Grand Underground, I actually did have fun with this.
But if I had to do a "choose one to keep and one to never play again," it's no contest. I'm keeping my Sword/Shield. I'm not even tempted to go Legendary hunting with Shining Silver. Part of that may be because I'm just tired after the grinding I had to do to beat the Champion. Part of it may be because I already have several copies of each of the Legendaries that I already obtained from the previous games and I just don't need the headache. But what it all comes down to is, I can't bring myself to finish absolutely everything this game has to offer whereas if Sword/Shield were to come out with more DLC, I'd probably nab it in a second.
I know this was kinda long-winded. But if anyone wanted it, here's the perception of one person who went into Shining Silver without having played the originals.