One of the main sticking points of Aquaman's critics is his lame powerset, specifically the only thing he ever really did in the Super Friends cartoon: Talk to fish. There's a reason Aquaman never tried to clear up this misperception, and he finally explained his dark secret in the first issue of DC Comics' recent gritty reboot.
Contrary to what the neckbeard/blatant internet commenter allegory asserts, Aquaman doesn't talk to fish so much as he commands them. The creatures of the sea don't choose to be bossed around by Aquaman. Nobody voted Arthur Curry in to Sea Kingship. They aren't his citizens but his subjects, and they're have no choice but to obey. In that short and frank conversation, Aquaman reveals his goofiest ability is actually his most appalling characteristic. You have to admire someone courageous enough to admit that they basically boil down to an underwater dictator.
Of course, many would argue that he only uses his fish slaves for good causes, and there's ample evidence, like...
Like any vague guardian/mentor figure who ropes a child into a life of underage crime fighting, Aquaman only wants the best for his sidekick. When a head injury jeopardizes Aqualad's chances of passing a school's admission test, Aquaman does the only rational thing (besides scheduling a makeup exam and/or a doctor's appointment): He orders his fish army to help his young ward cheat on the test.
It works beautifully. Aquaman has his marine plebes so well-trained that they have no problem whipping up a some living visual aids. Referencing the Mona Lisa is as simple as putting a ship figurehead together with some tentacles in the right configuration. The plan is executed so well that it effectively makes up for the fact that Aquaman let a boy in his care sustain mild brain trauma. Aqualad, still reeling from what is probably a concussion, seems to believe that the fish are "accidentally" forming these shapes that are jogging his memory.
In the end Aquaman succeeds, and his sidekick is successfully enrolled into a school that was built on the edge of a rocky cliff. It's a win/win; Aqualad gets to have an education that will help him figure out that a fish compass with English words was no accident, and Aquaman only has to put a minor in danger on weekends.
As far as super-weaknesses go, Superman's kryptonite is rough and Martian Manhunter's fire is even worse, but they're pretty weak compared to what the Sea King had to put up with. For years, Aquaman's biggest hurdle was the fact that he had to have water every hour or he'd die. Granted, it's not too hard for a dude who lives in the sea, but it can be a real problem when his pesky water allergy flares up, and it's always compounded with a secondary problem.
In this instance, we see the ol' familiar "I pledged to do a swim-a-thon but now I have a sudden water allergy so now I have to swim through other liquids that don't hurt me for some reason!" chestnut. There's definitely water in champagne, so Aquaman is putting on a brave face for the crowds while breaking out in hives.
Compared to the oil pipeline, frolicking in champagne would be like a day at SeaWorld. Then again, that would make swimming in liquid mercury like a day being one of the whales at SeaWorld. Since there is no mention of Aquaman's internal organs being poisoned by a lethal metal, we'll assume handed the baton to Jimmy Olsen for that section.
Multitasker that he is, Aquaman still finds time to stop some crooks while earning cash for seamen. His water allergy fades eventually, but as long as writers forget which story ideas have already been done to death, it'll always resurface.
It's safe to say that no other superhero comes close to Aquaman's high points. Who's laughing now?