Amazing sequel. The formula is the same as the first game - zombie horror, fixed camera angles, survival with limited amount of ammo/heal/saves mixed with point n click style puzzles. Great new setting, story and characters. Many improvements were made: better visuals, engine capabilities - a lot more zombies may appear in the same room than before; dialogues and voice acting - although still aren't perfect, good enough and much better than RE1. Two characters feature was expanded to separate, complementary scenarios for each, basically doubling the amount of unique gameplay in the same environment. Also, depending on who you chose first, the story will differ a bit. For the first playthrough I suggest starting with Claire, as this route is better IMO and considered canon. I only wish the base difficulty was a little bit harder, since towards the end you accumulate way too much ammo.
About the Dreamcast version: higher resolution than PS1, 60FPS and I noticed the sound stuttering a bit, although that might be an emulation problem. All the features from the PS1 Dualshock release are there, except it doesn't let you toggle the auto-aim in the settings, it depends on the mode you play - it is always enabled in the original game and disabled in arrange. Also, regardless of the region, Original game is now based on the PS1 Japanese release in terms of items and enemies spawn, and Arrange is the more difficult American version (new Expert difficulty doesn't have the free weapons from Rookie). For beating any scenario you unlock Hard and Nightmare difficulties for Original and Arrange modes respectively, which are great for replaying the game - enemies are a lot more dangerous, especially regular zombies who can either survive the entire pistol mag or die from one critical shot. Seems accurate, judging by the FMV cutscenes. There was no reason to not add this feature to the GC port.
About the Dreamcast version: higher resolution than PS1, 60FPS and I noticed the sound stuttering a bit, although that might be an emulation problem. All the features from the PS1 Dualshock release are there, except it doesn't let you toggle the auto-aim in the settings, it depends on the mode you play - it is always enabled in the original game and disabled in arrange. Also, regardless of the region, Original game is now based on the PS1 Japanese release in terms of items and enemies spawn, and Arrange is the more difficult American version (new Expert difficulty doesn't have the free weapons from Rookie). For beating any scenario you unlock Hard and Nightmare difficulties for Original and Arrange modes respectively, which are great for replaying the game - enemies are a lot more dangerous, especially regular zombies who can either survive the entire pistol mag or die from one critical shot. Seems accurate, judging by the FMV cutscenes. There was no reason to not add this feature to the GC port.