Funny thing, I just rewatched the movie that this was in and I noticed something. This technique, lightning tornado, and lightning saber are all used by the same person, and they didn't know chakra was a thing. They used the power of some special stone to use these instead. Which means none of those are ninjutsu, if you want to be technical lol. Anyway...
Trunks stands short range from his target and concentrates his raition chakra. Once he has enough gathered, he forces it out of all of his chakra release points and uses nature and shape manipulation while doing so. He uses nature manipulation to convert his raw chakra into lightning, and shape manipulation to bend it into a barrier around himself. Taking a moment to analyze the barrier, Trunks does a few punches and kicks to ensure that he won't electrocute himself if he makes the wrong movement. After figuring out that he is good, he takes control of the barrier and focuses all of it's power into one front, which he then releases in the form of a lightning wave to end the technique.
Since you specifically mentioned disadvantages, I am going to list those first. First, this can only be used up to short range. Normally, with a barrier jutsu, this isn't a big deal, and it isn't for this technique if I am using it that way. But if I wanted to use the wave, I would have to be at short range as well. Next, while this is active, I can only use lightning techniques. Now this is a disadvantage on its own, but there is another disadvantage that makes it worse. The disadvantage that I am talking about, and I believe that this is the one that you were referring too earlier, is the risk of electrocution. If my opponent were to use a medium-wide scale water jutsu while I have this active, I am done. Not only would this electrocute me on its own, but I can only use lightning jutsu, so stopping the water before it hits me or dodging isn't an option.
There are also a few advantages as well. First, it requires no hand seals, and everyone loves a quick defense. Next, it is a defense that I can move with without being restained, which is a huge advantage over other defenses. Earth walls, fire walls, and wall summons are cool and all, but they stay in place, so it leaves me undefended if I need to move. Samurai armor, and certain earth armors can defend really well, but slow you down. This technique is the best of both worlds. Last, it can be used offensively or defensively, while lasting multiple turns. This means I can use the defensive capabilities for the first two turns, then release the wave on the last one so that I spend 35 chakra in total instead of 20 this turn for defense, 20 next turn for defense, and 20 the third turn for attack.