I've been a fan of Spike Chunsoft's work since I first played Danganronpa. I played the first game in this game set (Nine Hours, Nine Persons, Nine Doors) a year or so ago. This review will primarily focus on the second game in the set (Virtue's Last Reward).
999 was a great starting game to the series. You will investigate multiple timelines in order to get the information necessary to complete the game. 999 is a great entry point into this mechanic. You get to know the characters well throughout the game. All in all, 999 will take roughly 10 hours or so to beat. Playing 999 is necessary in order to truly appreciate the rest of the series.
Now, Virtue's last reward...this is a MUCH beefier game. It took me just over 40 hours to complete everything in the game. Having an understanding of 999 is necessary to understand a lot of what is happening in the story of Virtue's Last Reward. The puzzles included in the game can be pretty challenging. There is an "easy" mode for the puzzles if they prove to be too challenging. There are also a lot of hidden things that you can find. As a fan of the series, finding all of the hidden files was very rewarding. There are also some rewarding easter eggs for those who have played the first game.
When judging the value of the game, this game has a LOT of substance. One of the best quality of life features is that you can fast forward if you've seen entire scenes before. It makes the experience A LOT shorter. Some of the content can be a bit dull at times and it can feel like you are being beaten over the head with information about physics and what not. However, you no not need to have a background in physics to beat the game.
All in all, I enjoyed this experience and am really looking forward to playing Zero Time Dilemma!