T2X is a nice addition to the storyline of T2 main game. That you don´t play as Garrett might feel a bit unusual first, but then it´s a refreshing experience. They designed everything to fit it to Zaya: The health bar, light-gem, player sounds and even the weapons are different(although the KO hammer is just a disguised blackjack).
There are also a lot of custom designed NPCs aside a few standard ones. Even the voice acting is mostly custom. Cut scenes are mostly made well, however I prefer the "paper" style over the animated scenes which look a bit like a game from the mid of the 90s.
The campaign also features a great soundtrack that is on par with the official one.
Level design is a mixed bag - most of the levels are ok, some even great, some could have been a bit better, especially the last should have been a bit more exciting.
Difficulty is also not that demanding - mostly there is no "no kill" restriction(only in one level aside some ghosting restrictions). I don´t know if it´s just for the difficulty not to be that high or because the character is rather different compared to Garrett. I presume the latter one, as a young woman on a quest for revenge is the protagonist, in the end it is up to player if he sneaks around or goes out for a massacre(even of civilians).
The new weapons are fun - however some don´t work that well. I found the ice arrow very useful, and the confusion arrow big fun.
The story itself is ok - it adds itself in to the events of the original games. Nothing special but solid.
Overall I would recommend this campaign - despite the flaws surely worth playing.