You know I speak truth. Even if dumb ol' Sableye 'n Sharpedo actually were of such high repute ya hold 'em in (they aren't ), they cannot make RS any less shittier.
Multiple small features introduced in GSC were outright removed in RS, for no apparent reason. One'a the most often complained 'bout would be day-night cycles bein' removed. Apricorns 'n headbutting trees disappeared. These're the most minor of issues I have with RS; but issues none the less. There's no need t' remove such things. Also, the text looked bloody horrible.
Next, an issue many people have a problem with whether they know it or not: a complete lack of things t' do in the post-game. GS gave you good ol' Kanto t' explore once again. DP had the Fight Area 'n Stark Mountain, as well as small post-game things t' do all over. BW1 had half the continent still unexplored 'fore beating the Champion; which ya still actually have t' do. What did RS offer? ... Completing your dex. That's it. The "post-game" objective which has existed since RB. RS took away small things and added nothin' in return regarding actual content after the Champion was defeated. Utterly boring.
Speakin' of content, this is where everythin' in the Pokemon series becomes notorious as bein' rinse and repeat. Get badges, disband the generic bad guy team(s), become a Champion. RS' "story" was palpably copy and paste. The same could be said for DP, but at least the Galactic goons had some amusin' lines...
Now I'll whine over the 'mons themselves. Retired Pokefans have long since complained that new designs have been right-shit since Gen 3. That's a complete load'a nonsensical, biased bullshit, but said exaggerated opinion does have some legitimate roots. I've always felt that RB and GS had a very unique charm 'bout essentially every Poke's design, minus the usual suspects of Voltorb 'n friends. I felt that appeal almost-entirely vanished in RS. Even if the designs weren't shit (they certainly weren't), they lacked in somethin'. I can't put it into words in all honesty, but whatever it is, it's a problem. Furthermore, I don't feel the same for DP and 'specially not BW's pocket monsters. Gen 4 reversed whatever terrible thing Gen 3 might've done, whereas I felt BW's new Pokemon had taken yet another step in the right direction regardin' successful designs.
Finally, quite possibly the biggest problem of all: RS was simply a disappointment. It took things away from GS, no longer had the charm the retro PokeRPGs had both in gameplay and 'mon design, was lacking in content compared to the past generation, and the only new thing brought to the table was sporadically encountered Double Battles, Abilities, and the start of minigame trends in the mainstay games (i.e. contests, musicals, etc.). The latter most addition isn't worth much merit. The former two enhance the depth of battling, but there's no difficulty in-game for that t' make things more enjoyable.
That's the bottom line. Lacking in ingenuity, content, and possibly even the love Generations 1 'n 2 received during development, RS is a failure. Bad games? No. Bad in comparison to the other RPGs within the main series? Damn right. 'Specially GS. RS just couldn't stand stand up to the Pokegames that preceded it. Perhaps if Hoenn was Gold and Silver whereas the brilliance of Johto 'n Kanto in one game was the third Generation, my opinion would be different... but sadly that ain't the case.