Final replay of Gens 1 to 3.
Yeah, it's not really good. Despite its quirks, I think the Gen 1 games are pretty good and cool considering the context of its development and release. The game systems are broken but they work well within its own gameplay logic. When you change those systems and leave the game as is, it suddenly stops feeling right.
I have a lot of nostalgia for the Kanto games, Yellow being my first game ever and being a kid during Gen 3. Having an updated version of RBY that looks more modern, feels thousands better to play than the original (everything is faster, modern boxes, etc) and having the new Pokémon in it is great. However, the game's balance is barely altered from the originals while implementing Gen 3 moves and mechanics. This results in, for example, boss battles with a 10 level difference that were winnable in the original suddenly requiring grinding due to more optimized enemy AI and movesets. The amount of trainer battles and samey teams are also unchanged despite it being fixed in GSC/RSE, and you also can't avoid them either because you can end up very underleveled. I feel the laziness to fix these issues and defend them as "fidelity to the originals" would appear again and much more strongly in HGSS, leading to the famous level curve discourse. I think that no definitive version in any main game of a generation needs any grinding at all, it just comes with bad remake balancing, the difficulty of gen 3-5 being the highest in the series and a misconception that you're supposed to be at the same level as the gym leaders when you fight them.

The new postgame content is ok I'd say, nothing special but appreciated. I can't tell why but I feel like the design of the Sevii routes come straight from a hackrom.