Here is my review of Zero Time dilemma from the steam store. It may contain a few spoilers though.
Even though this game did not work on my PC, I had to play it via 3DS. However this series has been amazing, the puzzles, the story, and atmosphere make this game one of my favorite games that I have played in a long time. I highly recommend playing 999 and VLR first to understand the circumstances of Sigma, Diana, and Phi and Junpei and Akane. It is easier to follow this way. Even though this wasn't my favorite game in the series, I still loved playing it and getting the conclusion to the first part of the series. I highly doubt this is the end of the series, and there will be a 4th volume in which I am certain will be as good or better than this game. The only thing that I didn't like was that it did not provide as many updates on past characters as i thought it would. Overall this game is amazing, and I highly recommend buying the 999 remake when it launches on Steam and Vita. As well as Virtue's Last Reward which is my favorite, I am hoping that the remake for the first game adds a flowchart and maybe additional endings.
Overall for me the series has gotten.
999: 9/10 VLR: 9.5/10 ZTD 9/10