I have not had the parka for long and since it hasn't been very cold yet, I can't tell that much yet about retention of warmth. But I get the impression the inner liner is very good. That said, I did have the opportunity to wear the outer shell in downpours and can tell you it is absolutely waterproof and windproof. That 20k water column is probably true.
The quality of the material is soft to the touch and construction is excellent; I'd say in line with my other high end technical gear (Arc'tyrex). You can wear a fleece or something like an insulated jacket (like an Atom LT) underneath the outer shell on itself too. But once the colder weather gets here I think the inner liner combined with the outer is a stellar combination. I don't expect to wear the inner liner in itself very much to be honest since I have other options, but that's no problem at all. So, all in all, a technical yet stylish and very good looking jacket that has been designed and build very well. I'm a big fan!