Purchased the Large-33.
They pack down fairly well; the side zip comes up from the ankle to mid hip so it is possible to access pockets in the trousers/shorts underneath. Second to keeping you dry they are very easy to remove/put-on without the need to take off walking boots, with more than enough space to avoid covering the inside of them in mud from the boots as well.
All in all excellent value for money. If I could change anything on them I'd probably have included a stuff sock for it, side pockets as well... but at sub £50 they do their job well.
While I fit smack in the middle of a 32-34 waist, I had to chose between medium & large; given it is an over trouser and some comments had suggested ensure you go up in size rather than down if borderline I went for the large, these are indeed a perfect fit. The longer leg is also perfect for my height (6' 1"); these have proven durable in the British weather so far for treks, with the leg comfortably sitting over the boot without scuffing the ground.