The spirit of this thread is to note problems and changes made to ports released of retro and arcade games. We're talking gritty, ridiculous levels of detail whenever possible - missing frames of animation, glitchy sound, filtered and blurred graphics, missing slowdown, extra slowdown, 240p/480p support, arrange soundtracks, censorship, scanlines, 50/60hz options, TATE/YOKO modes, all that good stuff. "It plays fine" isn't the same as arcade perfect.
A lot of this, just out of necessity, has to come from third-party sources. Sites like TFP Fanitsu, ASSEMbler Games, Neo-Geo.com, Gamengai, The Next Level, Hardcore Gaming 101, and numerous others have a wealth of info if you're willing to do some digging. The basic goal is simply to get enough info about a particular release to help people searching for these games to make a more informed decision.
Particular platforms of interest: PC Engine, PS1, PS2, Saturn. Common sense tends to indicate that NES, SNES, and Genesis ports are gonna suck, so it's probably more useful to note which ones are actually good than which ones are lacking.
Whenever possible, try to keep your notes brief and to the point, and pay very close attention to the release region.
Akumajou Dracula X: Gekka no Yasoukyoku SAT/JP - Includes some extra equipment and an additional character, but suffers from fake transparencies, poor load times, and muddy graphics.
Arcana Heart PS2/JP - 480p support missing (arcade was 30Hz 480p)
Arcana Heart PS2/NA - 480p support missing (arcade was 30Hz 480p), Japanese voices removed from story mode, pre-battle, and victory screens, but retained in battle.
Art of Fighting Anthology PS2/NA - Arranged soundtracks, but blood has been removed and some voice samples were cut.
Bakumatsu Rouman: Gekka no Kenshi 1-2 PS2/JP - Frame rate stutter, arranged soundtracks are distorted.
Castlevania: Symphony of the Night PS1/NA - Real transparencies, better load times, cleaner graphics than SAT.
Darius Gaiden SAT/JP - Fewer colors, dithering on some bosses.
Deathsmiles 360/NA - Arcade, 360 and Mega Black Label modes, with standard and HD display options, depending on selected mode.
Dennou Senki: Virtual On SAT/JP - Poor framerate, no single-frame cancels, numerous changes to attack damage and movement speeds, Belgdor can shoot through obstacles, no visible hills on Green Hills stage.
DoDonPachi Dai-Ou-Jou PS2/JP - Arcade perfect.
DoDonPachi Resurrection 360/EU - Region-free, TATE support.
DonPachi SAT/JP - Poor sound effect quality, excess slowdown, squished scaling if played in non-TATE mode.
Espgaluda PS2/JP - Arcade perfect, includes arrange mode, superplay footage, fixes graphics glitch when too many ingots are on screen.
Fatal Fury: Battle Archives 1 PS2/NA - Mostly arcade perfect, with arranged soundtrack, but blood has been removed.
Fatal Fury: Battle Archives 2 PS2/NA - Mostly arcade perfect, with arranged soundtrack, but blood has been removed.
Fu'un Super Combo PS2/JP - Arcade perfect with arrange soundtrack option.
Garou Densetsu: Battle Archives 1 PS2/JP - Arcade perfect, uncensored, arranged soundtrack.
Garou Densetsu: Battle Archives 2 PS2/JP - Arcade perfect, uncensored, arranged soundtrack.
Gekirindan SAT/JP - Additional slowdown, jittery scrolling and scaling effects, FMV ending.
Groove on Fight SAT/JP - Tons of missing frames and crap load times, but it does offer an arrange soundtrack.
Gwuange XBLA/NA - Arcade and 360 modes, with different controls depending on mode, TATE support, switchable between original and HD graphics.
Hyper Duel SAT/JP - Arcade perfect.
Ibara PS2/JP - Forced filtering, but reportedly not quite as bad as Mushihimesama.
Ikaruga XBLA/NA - TATE support
King of Fighters '95 SAT/JP - Arcade perfect, though characters aren't animated during order select.
King of Fighters '96 SAT/JP - Game crashes if you beat the game with an edit team, some sound dropout and voice samples cut short.
King of Fighters XI PS2/JP - Includes 480p support, which was present in the Atomiswave original, shorter load times than arcade.
King of Fighters XI PS2/NA - 480p support has been removed, retains shorter load times of the JP release.
Marvel Super Heroes PS1/NA - Missing frames of animation, poor load times, no tag outs.
Marvel Super Heroes SAT/NA - All frames intact with 1MB expansion, but causes horrible slowdown.
Metal Black SAT/JP - Arcade perfect.
Mushihimesama PS2/JP - Forced filtering and blurred into oblivion.
NeoGeo Battle Coliseum PS2/JP - Includes 480p support, which was present in the Atomiswave original, shorter load times than arcade.
NeoGeo Battle Coliseum PS2/NA - 480p support has been removed, retains shorter load times of the JP release.
Pocket Fighter PS1/NA - Missing frames of animation, poor load times.
Radiant Silvergun XBLA/NA - Includes Arcade and Saturn modes.
Raiden III PS2/NA - TATE support
Raiden IV 360/NA - TATE support
Ryuuko no Ken: Ten-Chi-Jin PS2/JP - Arcade perefect, arranged soundtrack, uncensored, no voice cuts.
Samurai Shodown Anthology PS2/NA - Forced filtering, in-game loading.
Sol Divide PS1/JP - Save system was removed entirely.
Sol Divide SAT/JP - Arcade perfect.
Street Fighter III: 3rd Strike DC/JP - Dudley's Punch & Cross from the arcade is missing. May have been a glitch to begin with?
Suggoi! Arcana Heart 2 PS2/JP - Tons of slowdown and lag, reduced graphics quality, forced filtering. Basically unplayable.
Sunset Riders SNES/NA - The women wear longer dresses, woman enemies have been removed, and the Indian enemies have been replaced by cowboys. Rakes have been removed from the levels. Chief Scalpem was changed to Chief Wigman. Some bosses have slightly different dialog. On level five the lift has been removed.
Sunset Riders GEN/NA - No voices for the bosses. Only level one, four, five, and a new level remain. All the levels have been modified. Each stage is also split into two parts. Bonus stage has been changed to a horseback riding stage. The boss from level six has been moved to level four. Only two characters can be used.
Wizardry: Proving Grounds of the Mad Overlord NES/NA - Floors 7 and 8 have completely changed from the Apple II version and are more difficult. These maps are also used in the Japan only release of Wizardry: Story of Llylgamyn Also armor class does not work and has no affect on damage taken. The classes Priest and Bishop have been changed to Cleric and Wizard.
Wizardry: Proving Grounds of the Mad Overlord PC/NA - In the PC version there is a glitch where you lose stats more often when you level up than all other versions of Wizardry.
World Heroes Anthology PS2/NA - Mostly arcade perfect, with arranged soundtrack, but blood has been removed.
X-Men: Children of the Atom SAT/JP - Missing frames of animation.
X-Men vs. Street Fighter PS1/NA - Missing frames of animation, poor load times, no tag outs.