Breja: What bothers me about him is why is he not wearing his Green Lantern costume when he's clearly using a Green Lantern ring?
Braggadar: Guy Gardener's garb has been depicted a few times as being vastly different than the traditional "spandex" sleek suit (for example: Batman the Brave and the Bold).
In the teaser trailer he actually IS wearing a variant of the suit, as depicted by the symbol on his belt. Unfortunately the over-saturation of the green lighting in the scene washes out the green colouration of said costume... I'd say it's a much deeper and more subtle "serious" green rather than being vibrant. Looks like they chose more white in his outfit than other styles I've seen though.
I know the symbol is there (on the sleeves too) but it just doesn't look anything like his comics costume at all. You're right it's probably the light that makes it look like he's wearing the same exact colors as Mr. Terrific, but even so his costume still looks like something out of the Arrowverse tv shows. For a second at first I even thought they were going for something more like
this (I had poor memory of that costume before I searched for it). I guess we'll have to wait for a better shot to really judge, but what little is here I don't like at all.
Then again, I think even Superman's costume looks rather bad and cheap.