Ok, Ill dissent. Aquaman cool? No. Never. EVER. As long as the "seaman who can talk to fish" jibb can be made, Aquaman will never be cool as the character will always be the butt of a perpetual joke. Not simply because of juvenile humor, but he suffers a fate amongst his DC peers worse than batman not having any superpowers. His entire arsenal is really only viable on this planet for a dominion that is functionally unpopulated. In order for Aquaman to effectively be involved in any of the normal adventures any of the other JLA chars have, there has to be a scenario specially crafted for him to combat, instead of being able to go against any potential threat with some measure of success. So ultimately his "usefulness" has always been incredibly limited, and THAT is the biggest reason he is always been the butt of the joke.
Hes like your little brother when you were a kid wanting to play baseball with the other kids, but was barely able to pick up the bat without falling over from its weight. At best, all the other kids are simply being nice and humoring his presence.
So knowing he is always going to be an inferior, second rate super hero, he is never going to be cool.
Now is it possible for aquaman to not entirely suck? That at least seems more plausible. Especially as they have been working hard across multiple incarnations of the char to play up the "king of Atlantis" and downplay the "talks to fish", they have been making slow inroads to a more tolerable aquaman.
And more over, I genuinely like the Mamoa look, as like I suggested, it plays more to the king of Atlantis, and less to the "fishyness" of it all. Battlefield earth comparisons and all.