Isn't this already out though? Either way, you're not missing much outside of "SOMETHING'S HAPPENING! IT MUST BE A PARADOX!!! :byodame:".
The ending is so good though. I also enjoyed the rest story and all the expansions (or retcons if you prefer) that were made to the narrative. Hell! I can go as far as saying that XIII-2 is the reason why I have been interested in LR.
And again, this is where you and I differ in opinion. I'm sorry, but I just can't take a villain with an instant "I WIN!" button built into his chest seriously, especially if there is literally nothing stopping him from pressing it at any given moment except for his own laziness and wanting to obtain maximum levels of douche-baggery.