I'm actually REALLY happy with the New Game+ mode. I was right at the end of the campaign and waited for NG+ to drop before I finished it all the way and restarted. I love all the extra cosmetics. I'm huge on photo mode and aesthetic, so having new gear available is always great.
The new charms can be used to either provide more of a handicap, or just make the gameplay a little more interesting. One charm adds a chance for lightning to strike opponents when using Heavenly Strike, one allows you to sneak up on Mongol dogs and befriend them and use them as allies, one of them just makes combat bloodier. Some of them make you use double focus for abilities, or other handicaps.
The customized load-out options save a ton of time and are a great QOL update.
Overall, it's not just a multi-player mode, but an awesome single player update as well.