As I recall from my 1 solo-ish skydiving experience: The standard rectangular parachutes let you move at a max of 20mph (or km/h?). And that's relative to wind. If the wind is 21mph, you can't go against it as an amateur.

I figure the round chutes are even worse at this, so you could be forced in one direction against your wishes.

From what I can see here: the chute deploys as soon as you eject at some hundreds of mph. It's probably big and therefore not very controllable.

Finally, I think you land in the seat, so it's hard to control your landing.