People book it with me because it looks like the soft option, and a fair number spend the first class quietly appalled. I do enjoy that, and I should probably warn you properly, so here goes.
Why the misunderstanding happens
Two things. There are props everywhere, and props read as assistance. And there is no flowing sequence, so it does not look like exercise from the door.
Both readings are wrong. The props are there to make a position more exact, which usually makes it harder rather than easier, and the absence of flow means you cannot use momentum to get through anything.
The actual difficulty
Duration and precision, at the same time.
Standing in one position for several minutes while somebody keeps refining what your back foot is doing is genuinely demanding, and it demands something most fitness has not trained: staying in one place while continuing to work.
Flowing practices let you leave a shape as soon as it gets uncomfortable. Here you do not, and that is the entire proposition.
What it is good at
Finding out what you actually do. Held long enough and set up precisely enough, every asymmetry and every avoidance becomes obvious, first to the teacher and then to you.
It is also, because of that precision, the tradition people are most often sent to when something hurts. Not because it is soft, but because it is exact, and exactness is what an injured body needs.
Who should try it
Anyone stuck. Anyone who has been practising a while and suspects they have been getting away with something. Anyone with a specific limitation.
Anyone bored, actually. It is a completely different intellectual proposition from a flow class.
What to expect from the first one
To be surprised at how tired your legs are, to have understood roughly a third of what I said, and to find the following morning informative.
Come three times before you decide. One class of a method built on refinement tells you almost nothing, and I would rather you judged it properly.