So once again, like all illusionary techniques, you use your chakra to disrupt the victim's. In this case it will affect their vision causing them to see a massive ball of fire falling from the sky suddenly. So this genjutsu is fairly obvious and as such it will only open up a seconds window with your opponent, if even that. Since it is so massive in some situations an opponent will barely have to move their eyes to see it. The genjutsu itself only affects vision so they don't feel the burning, as you said.
The analysis to escape the genjutsu, as you said, is very easy. There is no burning sensation so logically it means they are only seeing it. That leads the victim to believe they are under a genjutsu which affects their vision. Additionally the ball of fire appears suddenly. No hand seals required for it. No release of fire from the user. It just appears out of no where.
So to use this to your advantage you have to use a very fast attack afterwards in that window that you create that causes the opponent to look up. A raiton would be best for this as they are incredibly fast and dangerous.
Overall it is a pretty meh technqiue. I won't be using this one too often.
The analysis to escape the genjutsu, as you said, is very easy. There is no burning sensation so logically it means they are only seeing it. That leads the victim to believe they are under a genjutsu which affects their vision. Additionally the ball of fire appears suddenly. No hand seals required for it. No release of fire from the user. It just appears out of no where.
So to use this to your advantage you have to use a very fast attack afterwards in that window that you create that causes the opponent to look up. A raiton would be best for this as they are incredibly fast and dangerous.
Overall it is a pretty meh technqiue. I won't be using this one too often.