Same Old Gameplay, Graphics & Sounds
Unlike the remakes of the First Generation in Pokemon Fire Red and Leaf Green, the Digital Copies of the originial games are the exact same. This includes Gameplay, Graphics, and the Sounds. Some of these desirably needed a face lift, but some of the nostalgic features are still appreciated.
Even though they have been released for the 3DS, the games are still in the 2D Animation with the obsolete graphics and all. The newer animation still doesn't have the best looking graphics in our current world of technology, but they still shine above and beyond over the original games. A re-release isn't expected to change much of any game really, but some graphical enhancements with sprites and buildings and a better quality of sound would have definitely put the release over the top. Just look at the picture of the graphical changes over the generations above; a touch up would've been great.
Be that as it may, some of the old features, including the sounds made in battle, around cities, and between routes couldn't be better. Aforementioned, the quality of sound could've definitely have had a few minor imrovements, but the music that plays during your journey and what so many older Pokemon Fans love is the same, and just perfect the way it is.
Not much has changed, some things worse than others, but that's what the remakes were made for.