I like him, some of his sense of justice is ****ed up, he blew up the ship of innocent people in Ohara, which was quite ****ed up as he thought there could possibly be schoolers on the ship, he destroyed the ship, along with many children on it just for the sake the schoolers don't get out alive, which proves, akainu is willing to go to depths as far as killing other people to preach this "so called justice" or eradicating enemies which might cause trouble, this personality might overall be considered sadistic and very violent, but IMO it suits a role pretty essential for a villain/Antonganist.
As far as what I don't like, he's willing to kill his own comrades if they were not worthy to be marines, as he did with coby, and another marine, while the other admirals have shown to be pretty caring towards their fellow marines like kizaru and aokiji. But have shown their ruthlessness in battle, while akainu isn't like that, he's willing to resort to cruelty, brutality to achieve the goal, which could be for reasons of justice or otherwise. Which IMO makes him pretty different among the other admirals, and somewhat interesting. As for killing ace, It was a sad moment, but I wouldn't hate him for just killing a character, ace's death was a good reason for luffy to change his mind and train with Rayleigh so he won't allow the same to happen to his freinds, the point, it was their initial purpose to kill ace at that time, even garp was standing upto the pirates, if akainu wasn't there, it could've been someone else, it could've been anyone, that's just one thing, kizaru also engaged to kill luffy at that time, when Ben backmann interfered, since all the marines were fighting for the purpose to successfully hold out his execution. So I don't hate akainu for that. I like him as an antagonist, he makes a rather mysterious one, with a different perspective, and also after having sengoku recommended he wanted aokiji to be the next fleet admiral, akainu willingly fought him on that basis. His character makes me seem interested. I don't hate him. In my eyes, he's pretty interesting and I like villains like that