He's literally one of the best written characters in the entire series
He has an awesome design, and powers.
However, look at all the things the man can do:
- He is a D who is uber strong like Luffy
- He is a stoic swordsman who can cut mountains, and right hand man like Zoro
- He can steal anything in his room like Nami
- He is a brilliant tactician like Sanji
- He is a doctor like Chopper
- He can snipe any target from afar as long as they are within his room
- Now, he has an interest in the Poneglyph.
What's the point of having a crew with different abilities if Law can do almost everything. In addition, Oda admitted that he never intended his character to exist, and to be that prominent. Nothing wrong with adding a character that was not planned as long as he doesn't blatantly overshadow the main characters or supporting cast. Shikamaru from Naruto is a good example of a great supporting character ( the fact that he is lazy, and flawed makes him charming). Imho, Law has become the equivalent of Sasuke in the TS.