>>537682601 has definitely aged especially poorly. It's still fun to play but has some serious rough spots.
2 is much better but still feels way more ancient than 3 and beyond. Still, aside from obvious lacks like abilities and the clunkier box interface, Crystal is still great.
3 still feels super smooth and basically like the start of non-ancient Pokemon. It's modern-feeling enough that the newer features it lacks like better breeding items or physical/special move split feel more like an omission than "oh well, it's ancient".
4 has some serious framerate and battle speed issues. When it was new I thought the scaled-sprite thing in the overworld looked a little bit jank, and still do.
