While i am writing this review,i do it as someone who has not played the game,
So the plot is exactly as the sypnosis mentioned,its repeated but its done with variations in events as not to get repetitive even though the basics of the plot structure remain the same,althought even though i have not played the game i can tell some events are rushed to fit the 12 episode structure.
The character designs are unique and the art was great,i searched to see how the game designs look and they did very good in being accurate and looking good.There is quite a lot of CGI but its done very well and it fits very well with the rest of the animation,which is also good.
The VAs fit the characters very well and the music matched the style of the show and the opening/ending song was on the good side as well.
The main cast is fleshed out really well,moreso the main character Neku,although the villains are on the weak side as they were not fleshed out enough despite having motivations and enough presense.
Overall even as someone who has not played the game i can tell that a lot of things were rushed as you may have guesed from my review but as a standalone i believe the positives outweigh the negatives.