Honestly, underwhelming is an understatement.
I wasn't a big fan of the original squid game series but the concept as a TV series was cool and have you hooked immediately on the first episode.
The game series tho, it's almost bizarre and especially underwhelming for the final episode. It is not because of the original concept itself but more so to do with how the concept doesn't really work for a game show/contest.
When you are watching a reality show or game show, you always will have a or some contestants that you are rooting for. Not only because of how well one is doing within the contest, but it can be because of their personality or how they stand out. Those will get more frame time or "highlight" if you will, to talk about their background or how they're doing in the show itself. Typically, this is how the audience get "emotionally" invested in a contestant or a "character", whether it's in a positive or a negative way.
However, in this contest, the ones that stand out in the beginning, the ones that the audience are familiar with, the ones that you root for, literally ALL of them get eliminated one by one. Which, understandably the nature of this particular game, standing out is not the best way to get through. So, at the end (the last few episodes), which should be the most exciting or nerve racking stage of the series, the audience are left with a bunch of "nobody" that literally barely had any frame time or highlight throughout the series. As an audience, you literally don't know who these contestants are because they were never (or barely) shown throughout the whole first half of the series!
The finalists and the winner, literally, only had frame time or were focused in the last 2 or 3 episodes I think. You are rooting for nobody or have no one to root for because you literally just don't know who they are. Which all and all, make the "grand finale" extremely underwhelming.
There is a true disconnect between the audience and the contestants on how a game / contest like this normally played out. Typically, if you see a contestant win a big prize (let alone $4.56 million dollars!), you as an audience will have some sort of emotion triggered. Whether it's extreme joy for them or sad that the one you root for didn't win. But in this instance, it's like, ah, this person wins. And then you move on to another show like the last 10 episodes didn't happen.
The only positive note is that they replicated the original squid game setting/background to a T. Unless. there was where it was originally filmed then no, nothing positive whatsoever.