As for Manafort’s personality and ethics, read Corey Lewandowski’s “Let Trump Be Trump.”
I don’t like seeing anyone being taken down by a Leftist witch hunt. But according to Corey, Manafort accomplished little for the Trump campaign, even in his supposed role as a delegate recruiter in the run-up to the GOP convention.
Seems to me it’s a plus for Trump that he dumped the guy.