Like the first game, making a review that is both informative and spoiler-free requires some careful wording, so please forgive me if some explanations seem odd.
First of all, unlike Hatoful Boyfriend, Holiday Star has almost no Dating Sim elements. It's a much more linear Visual Novel, kinda like the Ace Attorney series. You'll start out with one chapter, and after you finish it, you'll get another chapter. Finishing a chapter will also net you a side-chapter. These side-chapters are usually comedic in nature, and they're also often non-canon. Despite being non-canon, however, they do offer clues that will gain importance later in the game, similar to the "Archives" in Hatoful Boyfriend.
Being a more linear story, the structure is quite different. The meat of the first game was a Slice-of-Life-y high school story. In Holiday Star, each chapter revolves around a surprisingly large central conflict, each getting larger and larger (though, the stakes in the end don't quite reach that of the first game's BBL route)
. However, it still manages to achieve its characteristic combo of unbelievable silliness and heavy seriousness, so fear not. There are some rather good character-building moments (for both the new and old characters), but they don't feel quite as frequent. I really only have one complaint with the comedy. While first game certainly wasn't afraid to get referential and fourth-wall-break-y, Holiday Star seems to do it more often, and it felt just a little distracting for me.
There's one last thing I want to add. In the main menu, there's an option called "Radio," in which questions from the fans are answered. Based on the title, I assumed it was all audio, so I waited until the end to check it out. Fret not, non-Japanese speakers, it's all text, and as such, it's all translated.
Ultimately, Holiday Star feels more like a side-game than a sequel. Still, if you liked the first game, I do recommend it (especially since it's only four dollars). I hope it also gets an HD re-release; the original font isn't terribly reader-friendly.