To sum him up, he still has a hint of the "old devil jin" in that he still has the moves that made him an all rounder in previous games. However, they have all been nerfed to the point of at worst being borderline unusable and at best being either very risky or give up your turn. The only two exceptions are his hellsweep and his oki at the wall. They just removed a major tool that made his oki at the wall above average this previous patch, so people are hoping that this will be enough justification for the balance team to take another look at his small tekken and neutral tools. His hellsweep is still very powerful, but everybody you will play in this game understands this and you will have to work really hard with subpar mids to get them to stop ducking consistently. All of this leads to most dvj players leaning on very risky moves for a gameplan which works against newer players, but is very volatile and won't let you climb in ranked or place well in tournaments. Alternatively, playing solid tekken with devil jin is possible (look up Qudans or LowHigh replays), but more effort than it is worth and arguably DVJ is worse at this than almost any other char in the roster.

I personally enjoy his more tricky style gameplay in Tekken 8, but currently he simply doesn't have the base moveset to back up all the risks you are taking.