Serika (New Year) drops in with 4 other students competing for your attention in the event New Years' Rhapsody No. 68. If you don't have her yet, this article will outline whether she is worth pulling for or not.
Serika (New Year) is a Permanent 3* Piercing student whose main use is being a mob clearer in both regular content like events and story stages and endgame content like Chesed Total Assault.
As a Special student, she finds herself in an odd position. While she frees up a Striker slot for better DPS-oriented characters to steal the show, this also means you'll be one Support character short, and depending on where you're using her, the lack of buffers such as Ako or Himari may become problematic.
Not only that, she is an expensive investment to have, needing a minimum of UE40 to truly shine in battles where she specializes in, such as Chesed Total Assault.
She can still find herself in useful situations in general, however, owing to her large range for her AoE EX skill being able to hit a ton of enemies that.
A more in-depth review of Serika (New Year) can be found on here.
Unless you're a big fan of Serika herself, pulling on her banner is not recommended.
To start with, There are many AoE students that deal Piercing damage that are just as good if not better options, one of which you can already get for free (Nonomi). Another option is Momoi, who is a 2* and will likely spook your rolls when you're trying to get another student. You can easily get her elephs in Total Assault as well, making it easier to raise her.
Another problem is how expensive it is to invest in her. As mentioned earlier, you really want to get Serika (New Year) to UE40 to really shine effectively, which can be a huge ask, considering that you'll need an estimated 1500 eligmas to get her up there.
Finally, she just doesn't bring as much to the table compared to someone like Mutsuki (New Year), a limited student at that, and Kayoko (New Year), a permanent student but still one who is very important. Serika (New Year) herself is a permanent student, and thus can spook you in any of your future rolls.
Serika (New Year) is a waifu pull, but she can still work if you really intend on investing in her, otherwise, skip.