Better than micro-baffle down.
I love this fleece.
I`m 6'4 170 lb and the medium is perfect for my chest and arms although a little short in the body.
I wear this as casual wear in Scotland in the winter a lot probably 5 celsius to -15 celsius.(10-35F). It would be good for lower temperatures if you are being energetic and wind isnt to high.
The breathability is amazing and while it is about as warm as a micro baffle down such as my montane nitrous it is much better for active use. It dosent squash down quite as much as a down jacket and dosent have any wind stopping ability but it is a superb midlayer and it is nicely hydrophobic.
My current upper body winter walking system which is a joy in the windy subarctic cairngorms consists of a patagonia capilene 3 baselayer, the monkeyman fleece and a patagonia ascensionist softshell. For a tall + slim guy like me the monkeyman is a perfect fit. It also works perfectly as part of my no-membrane winter walking system.