I thought it was annoyingly nasal, artificially stilted and slow, and just made me punch a character who came off as "insufferable snob" more than "tactical mega-genius".
And why forehead prosthetics? The brows are there on most of the human characters. It's just part of Rebels' animation style. In all the depictions I've seen, the Chiss are basically Humans with blue skin and red eyes.
He was active pre-ANH, before the Emperor sent him out to the Unknown Regions. But he didn't have the Chimaera (which didn't have the stupid relief hull panels on the belly depicting the ship's namesake) or Pellaeon. It could have been done more faithfully -- and, I think, better -- if he'd been good but didn't have much in the way of a fleet or a big ship of his own... more low-key and easy for adversaries to underestimate... Give him a chance to build his rep with viewers through his actions, setting up for his eventual return later...