Well I've only had one complete run of the game (getting As first time of course ) But it plays pretty much exactly as the original. Multiple dreamies are in (and easier as the air brake happens less often and you can use all four shoulder buttons), ABPs work very differently though. Theres a proper Widescreen mode also. The dpad doesnt help for SM stunts.
The game does look great (esp with RGB cable - just wow). Not up to current gen PS2 games (Sonic Riders 2 for example) but still amazing to see for an old school Nights player like me... The boss battles look great (esp Wizeman!) and Twin Seeds probably seems the most drastically improved dream.
The wierdest thing is having the draw in line and horizons alot farther reaching. Its a bit disconcerting to actually be able to see the chips and ribbons from so far off lol
The original Saturn is very faithful from what I've seen (only played SV so far)
Things I've Discovered/unlocked as far
Xmas Nights remade (get all As?)
Nightopian Status (complete Xmas Nights with both - you'll find it in options)
'Winter Nights' Start screen (complete Xmas Nights?)
Elliot and Claris in tracksuits (complete Xmas Nighst with both?)
The last row in Gallery (complete Xmas Nights? includes Xmas Nights intro storyboard!)
REALA IS IN!! (Set internal clock to April 1st then play Spring Valley in ps2 mode - thats the only dream he is. Also (spoiler)...
Exit option in pause (was just in original Xmas Nights)
The clock features of Xmas nights that change the start screen work.
Negative Stuff/Things missing/Different at the moment -
No 2 player
Xmas Nights ripped to pieces (no original, no presents, no karoke, no music mood adjuster)
PS2 pad feels 'different' (need to play test it more though)
Xmas nights intro ('The city is covered in lights...' intro) is in Japanese - fun to hear though!
Gillwing paraloop technique seems tighter (I've actually not done it yet - got a 19 link max, his head doesnt seem to take hit from the paraloop any more)
Gulpos fish seem harder to grab onto
No Link attack, Time Attack or Sonic into Dreams...
No blue-out above Twin Seeds Tower.
Links are harder overall
Will keep updating this post with new stuff
Overall, worth it for a Nights fan (especially at the price - www.play-asia.com). I think unless some exploit is found, I might allow scores from the game in the main tables at sa.net