Take a look at that crowd shot. There are several people who do not have their hair braided or in a bun/ponytail. It should be wet and wavy, yet it looks perfectly dry (sometimes even spiked).
It may only be a single shot, but this is what people are talking about when they say the visuals remind them of Green Lantern. When there are people shown underwater, it looks like a bad composite job, with a poor integration of real people into a virtual environment. The creatures and overall landscape look pretty good, though.
This also may seem like a trivial concern, but Aquamans pants shouldve been torn off of him after swimming that fast at the start of the trailer. Characters like Superman or the Flash can pull it off because they have specially designed, full body costumes. Arthurs just wearing a regular pair of jeans.
As other people have sad, some imperfect CGI can be overlooked if the writing is up to snuff, but that doesnt seem to be the case here. A lot of cliche tropes, unimaginative dialogue, and ultimately I dont know what the point of view here is or what its trying to say.
I do think about it, and it does bug me sometimes. If the story is engaging I tend to care less, but the story conveyed in the trailer did nothing for me which is why other flaws stand out more.
I thought I'd already mentioned that.