I've just finished making the Magic Pants. I have done a step-by-step of the construction on my YouTube channel, Diane in Stitches, but the designer also has a sewalong video on her channel.
The written instructions are very good, and I just worked through those along with the video sewalong. It's a very interesting construction, and I love that the waist can be adapted to fit with the elastic and hidden panel, but it's not bulky.
I thought I'd read somewhere that they came out big, so I did a silly thing and sized down, although I was partially in both sizes for the waist size range, but I thought the hip ease looked too big on the Small so I made the Xtra Small and I do have a little bit of a struggle to get them on! But once they are on they are fine.