Resident Evil 3 Remake was my second game from the franchise after RE2 Remake so I will be comparing them a lot. The graphics are very well done, almost exactly like RE2R which looks absolutely beautiful. The environment is now brighter, unlike the dark hallways in the second game. Character models look fantastic and detailed.
This game is significantly more action-packed than RE2R. Much, much more chase sequences, boss-fights and less moments where you have to figure out your way through a labyrinth and less "key finding" moments. However, I would say the map is smaller and restrictive than the second game running around is less tedious but also loses some of its freedom.
The main antagonist is Nemesis, which is definitely not as scary as Mr. X from RE2. The problem with more action-packed gameplay is that most of them are scripted events, meaning that chase sequences aren't as terrifying but more has more action. For example, chase sequences in RE2 involves trying to "escape" Mr. X. What makes it so terrifying is that the chase duration isn't scripted meaning that he is chasing you throughout the game. HE DOES NOT STOP. You could easily bump into him again. In RE3 however, the chase ends after Jill jumps off a building or squeeze through a vent or something. This means that after a chase sequence, you can be sure that Nemesis isn't gonna appear again (for at least a period of time until the next encounter which can be unexpected). You don't have to constantly worry about him.
The biggest disappointment in RE3 however, is the game length. It took me 8 hours to beat Leon's story in RE2, which I still have Claire's story is complete (which is probably another 8 hours). In RE3 however, I beat the story in 6 hours. Jill is the only protagonist so after beating the main story there isn't much left to do but replay the game to get all the achievements or collectibles. Capcom spent time on a multiplayer mode for RE3 but most people don't play Resident Evil for multiplayer, they play it for the characters and story and bosses.
In conclusion, RE3 is a good game that is dragged down by its criminally short length of 6 hours. You DEFINITELY DO NOT need to play RE3 to play RE4, since none of the story is connected. RE2 and 4 are connected though. As someone who played all the remakes, if you are running want the full Resident Evil experience, RE3 is definitely worth a shot.