Of course, they work in real life. So they've got that going for them.
They're just G-suits, right? They're not rated for vacuum?
They *are* vac suits - it said in the launch commentary. They're mainly in case of the cabin depressurising.
One cool thing is that when they're walking out to the pad their hands are bare. Then, when they get strapped in, the gloves unfold from inside the sleeve cuffs. They slide their hands into them, then seal them with two layers of gas-tight zippers up the side of each sleeve/glove. So it's then all one piece, and they don't have clunky metal locking rings attaching separate gloves like you see on every other space suit. I imagine that helps manual dexterity and comfort quite a bit.
I have a suspicion that that might be the reason for the "wellies" - to get a good seal with the trousers of the suit. They do look a lot thinner and more flexible than actual wellies.