New Game +

Starting in v1.0.0, new game + will become available as soon as you finish the main storyline. You will be able to start the mode from your home; the option will appear right under the “reflect on your adventure” option. 

What carries over: 

• Your G, tiaras, unlocked outfits, and the butt plug.

• All of your ingredients and potions.

• Your alchemy rank and unlocked recipes, including recipes earned from requests and other world events. 

• Your perks, sexual experience, fetish growth, and social skill values. 

• Traits, including traits earned from requests, and your current TP and progress to the next TP. 

What doesn't carry over: 

• Story progress, completed requests, and the world state in general are all completely reset. For example, you you'll need to unlock locations like uptown and the coven again.

• Romances, relationships, and affinity with allies and factions are all reset. 

• You will need to re-unlock most special abilities (e.g., potion magic, create homunculus, kissing magic).

• Your key items (aside from tiaras and the butt plug), are all removed and will need to be re-acquired. 

• Your reputation values are all reset to 0. 

New game + vs starting a normal new game: 

Obviously, in a new game + playthrough, the game will be much easier right from the start, and this, combined with how much you'll likely have unlocked already, may deprive you of the satisfaction of normal progression. However, the benefit is you'll be able to quickly zip through the game to try new choices, experience different romances, pick up alternate request rewards, or just see some story moments again. 

However, if you're planning to play the game from the start in a more extensive way, starting over with a normal new game may give you a better experience. Additionally, some events and outcomes that may be interesting are locked behind lacking certain perks or abilities. Going in loaded up with all the traits and perks makes guards and notoriety a total non-issue, for example. 

Ultimately, I think for a full replay of the game, starting a normal new game is better, while the new game + mode is better for some lighter replaying, like touring alternate paths or seeing previously missed content. 

Of course, the choice is yours--that's just my two cents!