Twilight isn't having a very good day. An experimental spell blew up in her face, an army of changelings is attacking Canterlot, and she just died. Yet somehow, it looks like it's going to keep going downhill from here.
Given the chance to correct what's gone wrong, Twilight swears she's going to fix all this even if it kills her. Which it will. Frequently.
An absolute terrible story. Starting with "will I meet them on the other side", when he personally made sure that there is no other side and ending with absolutely stupid morality. The fact that an immortal will not be able to find a solution to such a problem for eternity indicates that the author is too stupid to at least partially represent an immortal being. Not to mention how stupidly the 1st and 2nd points are combined. There a meeting on the other side and saying that immortality is bad , real insanity
Twilight's caught in a Groundhog Day timeloop, but with a harsh twist - just five hours or so after the beginning of the loop the Changelings brutally invade Equestria again, and Twilight generally dies right afterward. This gives the story a much tighter and clearer plot than Groundhog Day. There's a definite puzzle that needs to be solved; the Changeling invasion must be thwarted, and Twilight has only five hours or so in which to do it.
As might be expected from that premise there's rather a lot of violence in this story. It's handled well, though, and the psychological damage of dying over and over and over again take their toll on Twilight without becoming overwhelming. It's quite interesting seeing all the different strategies that Twilight tries before finally finding the "perfect run".
An interesting feature of this story is that it's written in the first person with Twilight as the viewpoint character. As such, it really gets "inside her head" and in my opinion does a great job of it. It does go a bit outside the bounds of the character as defined by the show, but given that she's put in circumstances well beyond what the show puts Twilight in it seemed fair.