False surroundings is a genjutsu better used like, when the opponent isnt already familiar with the area around them. If you have a way of concealing yourself and having the first move, it can be a decent genjutsu to use early on. The gen itself is pretty simple, but can be complex. Changing anything from the location of a tree to adding and entire mountain range in front of your opponent. When used mid battle, you need to make subtle changes that are enough to throw off the opponent. One such example can be, while retreating, you can use the gen to make the opponent believe the landscape is slowly declining, making it look like you're decending down a hill slowly. If the decline is extremely slight, then after a few turns of retreating and countering, your opponent will, eventually, be sending jutsu down at the ground due to them thinking you're on an incline below them.
Yeah never much of a fan either. Its a simple illusion but it doesnt hold much merit. The handseals give it away the most, if it was handsealess i think it'd be better. As you vanish into the petals, the opponent loses track of you. Would be a good gen to use with a Clone, as once the movements are masked and you're striking them, the clone can get into a better position, but i dont personally see many practical applications on this one myself.