DiCaprio praises Belfort's honesty in his admission of mistakes, so it's not like he's praising what Belfort did at all.

He also praises Belfort's abilities as a motivator, and it's obvious Belfort is an exceptional public speaker and motivator.

But at this point, those who didn't like it and/or feel it's overpraised have taken to Twitter posting this video and Belfort's cameo at film's end as some sort of examples of Leo/Marty admiring Belfort's crimes. When, yknow, that's not the case at all, clearly.