This appears to be a 'very enhanced release'.
It contains all the DLC from the origiginal game, the Ayane Missions and it looks like the gameplay has been seriously revamped.
The first game was bloody but there was no dismemberment.
The combat enhancements may please those hardcore players who were turned off by the original "Ninja Gaiden 3" for being a different game than "Ninja Gaiden 2".
Just have a play through on Normal.
I dare ya.
The demo features an Ayane level and a Ryu level.
I've played the Ryu level in the original game and though the scene is the same it plays differently.
For those of you who like to decide for yourselves, download it and check it out.
For those of you who need to be told if you can like it or not, you may as well get a head start just in case you're told it's good.
Afs mentioned above all the Karma you bank will carry over to the main game.
Az