I grew up with both the first and second generations(like alder and smitie), and, comparing the first one with the second one, G/S/C improved a LOT, and I mean it.
Day/Night features, internal clock, real time events, TWO regions(the new region Johto, and a "futuristic" Kanto), 100 new pokémon, an awesome plot that didn't die after beating the Pokémon league, etc.
After that, came the third generation(R/S/E/Lg/Fr), and I got Ruby the day it came out, and what was my first disapointment?The lack of the day/night system, it was one of the reasons that made it pale in comparison to the second generation. Also, there was only one region, even though it felt slightly bigger than Johto.
Fr/Lg were remakes of the first gen, and I'm not gonna complain much about them, the only thing that really annoyed me was the fact that the Sevii Islands felt so bland, so... I dunno... empty... They could have done a second region like Johto, two years before G/S/C(for those who don't know, G/S/C and D/P/P are two years after the events of R/B/Y and R/S/E), but at least, they tried.
And then, the 4th generation arrived, and it is almost as awesome as the second. Nowadays, I've been playing Platinum, and I really get into it, like it was with G/S/C(wich I sometimes plug into my GBA SP and play for hours
), and it has an almost nostalgic feeling. Platinum is way above Diamond and Pearl, but even those have a very good plot, and interesting sidequests to do.
I hope you guys agree with me