so people that beat it.
How does it hold up compare to previous games in terms of difficulty balance (I'll probably be playing with exp share on), content, music.
Gen 3 is the only pokemon series i've never beaten because I didn't have a gba at the time and it looked pretty underwhelming graphics wise and content wise vs gold/silver.
Favorite pokeman games are gen2 ds remakes, and X2Y2 for difficulty and the weirdly mature story. Besides being the first game with 3d visuals, I was pretty disappointed with XY in terms of difficulty (gym leaders/e4 need more pokemon), and technical performance.
Wat
Assuming you typoed and meant your favorite games are HGSS and BW2, so are mine, so maybe I'll be able to give you a good idea of what you're looking for?
In terms of difficulty balance, the balance doesn't account for exp share, mega evolutions, dexnav special moves, or basically any gen 6 additions. So don't use any of those if you want any semblance of a challenge at all. Also don't use any traded pokemon (this includes the mystery gift Beldum) as those get boosted exp and will become overleveled quickly. Assuming you use none of these the balance is still not great, especially since bosses use their easier RS teams instead of their more difficult Emerald teams, but it becomes better around the point where you fight your version exclusive legendary.
As for quantity of content it's okay, better than XY. The main game is as long as any pokemon game, but once you finish the main story events the game really opens up and you can go legendary hunting and do some cool sidequests before you even head to the Elite 4. After the E4, you also have the Delta Episode which is great albeit short, and then in the post post-game you have the Battle Maison which is exactly the same as in XY and a bunch of new move tutors. There isn't as big of a diversity of pokemon available in Hoenn as in Kalos though, so that might be a negative for you.
As for quality of content it's great IMO, they improved the Hoenn region in a lot of ways, especially the water sections with lots of small details and little additions like underwater trainer battles. The only bad additions to the game are the new Mauville, which they could have handled better to make it fit in with the region, even more team Aqua/Magma fights, which start to get repetitive after a while due to their low diversity in pokemon, and some unnecessary hand holding, which is for the most part unobtrusive.
Music-wise the remixes vary from "they didn't do much to improve this song, but it was a decent song to begin with so whatever" (ex: Trainer Battle Theme, Gym Leader Theme) to "Holy fuck this amazing" (ex: Team Leader Battle Theme/Steven Encounter Theme). And every original composition for this game is fantastic, in fact most of my favorite songs in this game are the brand new ones.