No first hand experience, but they were a staple in Toronto. I know they are very warm, kept my friend cozy in our very cold winters in Toronto. But they are also very expensive so you have to decide if it's worth it... for typical winters here that I've experienced so far, they don't seem necessary, but would be comfortable. From what I've heard they're good quality.
A word of warning (and I won't post videos, easily found on the net- and horrific)- goose down is 'harvested' from factory farmed geese, mostly in Eastern Europe- where the feathers and down are pulled violently from the bird, alive- the process is repeated severalo times over a birds lifetime. I wouldn't wear one personally however light and warm they are. Same goose down duvets and pillows, etc.
Yes they aren't even remotely cheap, but they are the best and the materials reflect that... real fur lining on the hood too. They are a long-term investment, but only worth it if you will really get use out of them.
My parka is nice and warm and comes out when it is very cold and/ or very windy. It is not waterproof (but is water repellent), so I do not use if it is snowing (a bit of light snow is alright, though). The fact that it is not waterproof was a bit of a deterrent, but in the end, I am glad I went for it (it is certainly windproof ;o)).
Also note that most shops do not carry a big stock (it's bloody expensive), and so you may have to call the stockists before you venture to DE or FR.
And lastly don't buy online! There are too many fakes around and their sizes are a bit of a gamble - in some models, I could fit in a size S, but in others it was M and even XS!
Our daughter swears by her canada goose jacket (Mum and Dad paid for it ). My BH ordered me a down geox jacket on Zalando Lounge - great value and it is brilliant