Just completed it and have to say it's a brilliant game and stands up with the rest of the series.
There's a point when you start palace 6 where the game ramps up from a good game to a great game. The story advances rapidly, you max out most of your confidants, the music is amazing, the palaces are more interesting, you don't have to manage your sp as much and it's boss fight after boss fight after boss fight (plus another boss fight because 3 boss fights in a row would be too easy).
The weakest part of the game is Mementos. The music is uninteresting and the enemies are too weak (often filled with lower shadows than the palace you have just beaten). Grinding is definitely a chore here.
I don't think I'll play a NG+ because I've maxed out all but 2 confidants.
The most useful confidants by far are Fortune (level 7 allows you to increase affinity with someone every day) and Death (those 50k SP recovery accessories are awesome)
My party for the endgame was
All that's left for me to do to complete the true Persona ending is to aggressively argue online on who is the best Waifu