I guess the point for this is to milk the beach episode for all it's worth, and might as well help sell the visual book at the same time. This omake is just a short extension to the (fake) beach episode in the original series. Kuroko is up to one of her schemes again trying to er... "get closer" to her Onee-sama (Mikoto) when her plan accidentally got foiled by Saten, making Uiharu a victim. Hilarity ensues. The omake doesn't contribute at all to the To-Aru storyline or universe, but at least it's new scenes of your favourite characters. Even though it's intended as a comedy/fanservice projectit isn't really funny or ecchi, but I liked seeing Misaka again after a while the main series has ended. So while it's kinda worth watching for me, I can't say the same for everyone else.