Hmm, bit of a mixed bag here! There's definitely a lot of cool stuff in here, but at the same time there's a lot of clunkiness that either hasn't been addressed from the original or has been introduced in this version.
In terms of the good:
*I really liked the cutscenes added to the start and end of each level, along with the little dialogue bubbles on the bottom bar during gameplay: all of it added a great deal of story and character to the experience compared to the original. With this, I think the game is much close to its original Parappa inspirations.
*Overall the story was a pretty cool and inventive cross-over with a nice progression and ending, albeit a bit overly fanfic-y.
*I liked the left-over ghost arrows since they serve as a new feedback to let you know how accurate you were in your note presses.
*I liked the introduction of this whole new mechanic in the third act of having to dodge attacks while still dealing with the usual music gameplay: really adds a whole new level of challenge as you have to split your attention in a wild way.
*It did a decent job at recreating the FnF gameplay and style, for the most part: kinda laggy and a little rough, but mostly there.
And in terms of the bad:
*When I first played the game, since the story was all about Isaac and they're the one in the spotlight, I actually thought I was supposed to be playing as them. Took me awhile to realize I was supposed to be playing as Boyfriend, but can you blame me?
*I really wish the game would show the combo meter and the note grading feedback front-and-center on the note chart instead of putting them across the screen where it's hard to see them while playing: makes it really difficult to determine whether you're hitting the notes and keeping your combo going when you need to lose focus of the note chart just to take a peek.
*I liked the idea of putting dialogue on the bottom bar, but it was very difficult to read it when they were talking during gameplay, particularly on the harder courses where you're too busy paying attention to the notes. They should only talk during a slow period of the song, or you should have voice overs instead, perhaps.
*The third act dodging mechanic was incredibly awkward and confusing: not only does the game only display the tutorial message for barely any time and in a faded opacity so I didn't know what was happening for a longest time, but even when I knew what to do it was difficult to tell when you're getting hit or whether you've dodged and what were the obstacles and so on.
*It feels like the algorithm used for note accuracy detection was off and malfunctioning: not only did I have a lot of notes I felt like I should've hit perfectly get counted as missed, and vice versa, I was also able to get through the third act by just randomly mashing.
*I didn't like how when you miss notes, Boyfriend still continues to sing as if nothing happened when he should stop singing or painfully grunt. By losing this feature, you lose a critical sense of connection and feedback to the character that the original had.
*Boyfriend doesn't talk! He speaks in beeps and boops! You can't just give him normal dialogue bubbles like that: it's illegal!