There have been some improvements from the original games - for example, the use of the “weapon wheel” system rather than cycling through every item individually, making combat flow easier, and the addition of the modern GPS map system makes travel and finding specific destinations a lot easier - as does being able to instantly retry missions from a simple menu (though, a more robust checkpoint system would be a better improvement.) Additionally, as expected, the game loads faster than the original, and some scenes are improved graphically, though this aspect isn’t too impressive considering the age of the material and the improvements in hardware in the last twenty years.
To most, it seems as though the negatives outweigh the positives - one of the most obvious (and most laughed at) negatives being the character models. Character’s faces feel very sloppily done, some completely unrecognisable from the original games, with many looking overly shiny and extremely unnatural. Another very visible issue is the movement and posing of characters - in some versions of the game, animation frames are completely missing, meaning models snap to positions with no movement in between. In San Andreas specifically, the models have a horrific bike riding issue, wherein their elbows bend the wrong way.
A big disappointment noticed by fans of the original games is that most environmental humour is lost - billboards and shopfront’s cleverly constructed art and pun-based advertising has been removed or replaced by what could easily be “pizza.png” and phrases that don’t make sense anymore. Other textures have similar issues, the ambience of the environments are often disrupted by the greenest default grass texture or a very obviously stock image of blood on the ground. However, worse than stock images and lacklustre humour is the rain that can barely be seen through and tends to fall even while under bridges and indoors. Another huge disappointment is the removal of some of the iconic soundtracks. Smaller issues such as inconsistent frame rates and mismatched subtitles differ from platform to platform but are still causing issues for many players.
Overall, the salt in the wound with this game is Rockstar and Take Two removing all traces of the original three games from online marketplaces and launchers - as well as attempting to completely destroy and even sue modders who had already essentially remastered the game for free in the past, to make way for this version of the games - which ended up being a sloppy, upsetting and downright disservice to the original versions.