The biggest issue that stems with Future Diary is that it seems to get too fixated in advancing its plot head-on without any regard for proper depth, buildup and consistency. There are a number of unexplored elements to the series like how Yukiteru became acquainted with Deus and why many of the folks Deus chose for the survival game are a bunch of psychopaths, criminals and loons. Logic is tossed out the window with how certain plot setups occur and characters making decisions that don't make much sense like one character able to rig a ridiculous number of bombs throughout a school without anyone even noticing and Yukiteru continuing to trust Yuno despite knowing full well how much of a nutcase she is. A number of the players in the survival game don't get much depth beyond being crazed loons and criminals, and those who do get some sort of depth only get them in a scope of a couple episodes where their mentality for the violent and depraved acts they commit don't make any sense and seemed sloppily pasted together. The series lacks a consistent mood as it tries mixing around deadly serious storytelling and comedy at a number of points with the interactions between Yuno and Yukiteru, which felt awkward and ill-timed in execution. The final episodes of the series seemed sloppy in their execution with convenient developments and plot twists that either get convoluted or are poorly explored. And lastly, it tends to relish too greatly at many points in its graphic and depraved content with a good number of violent and gory scenes, a good amount of nudity and sexual content, torture, rape, child abuse, terrorism and a diverse number of ways to murder folks. It's like whoever made this series wanted to make it a seinen title, yet winded up with the immaturity and cheesiness you would find with a cookie-cutter shounen title in the way it is set up and structured.
The visuals to Future Diary are on the plain side with character designs sporting the typical mainstream look and scenery shots being decent with what they deliver. The CG animation for this (used mostly with vehicles or rendering the world of Deus ex Machina) is a bit sloppy as it looks awkwardly rendered and clearly sticks out from the typical animation of the series. The animation is nothing to write home about either with flat choreography during fight scenes and a decent number of animation shortcuts used throughout the title's run.
Overall, Future Diary is one of the biggest messes in quality that I've seen in a while from a title getting plenty of hype from anime fans. With no regard for proper depth, consistency and buildup in the treatment of its plot and characters, as well as relishing in its objectionable content and themes, Future Diary is a lovely train wreck of a title that may get either disgust or unintentional laughs from fans with its content and sloppy execution.
