First, I'd like to acknowledge the extremely subjective nature of rating winter clothing for warmth. I'm an ice climber and a skier that regularly recreates in temperatures below 0 F, so keep that in mind.
I've found all of the Utraz line to be incredibly warm given it's relative light weight and extreme low bulk. Most of my winter cycling takes place after work (i.e. in the dark) and I will happily wear my Utraz tights, jacket, and base layer for 2 hours +/- with no concerns. In fact, at much above 30 F, the Ultraz clothing can get to be a bit too warm, particularly if the sun is shining.
Ultimately, it's my hands and feet that turn me towards home during cold weather rides.
No high end cycling (or climbing or skiing or running etc etc) gear can be called "a steal", but given what we ask our winter gear to do for us, I gave the Utraz tights 5 stars and have been very pleased with their performance in weather that is really more suited for books and tea than cycling.
These are definitely a "Wow, these were disappointing" kind of product. Based on the description, I expected something that was significantly more suited for Winter wear. These don't remotely feel like they'd be good for Winter use, short of a layer that wouldn't fit below how they are, seeing their tightness. The chamois seems excellent, but never got to try it. The biggest detraction I found with these and the reason for which I ended up returning them, was the front portion of the bibs is barely above the waistline, which would inhibit keeping drafts out while riding.
Simple and solid performance in a winter bib, great functionality and fit, very comfy on long cold rides around 28-32deg, still very comfy and not too warm when mercury reaches 40-45deg. Excellent moisture management in wide weather variance.
I purchased these bibs to add to my winter wardrobe. In past winters, I almost exclusively rode in bib shorts covered with an older Assos overall type zip up bib. In spite of these zip up bibs being supposedly windproof, I found them not be keep me warm enough.
Today, my new Mille Ultraz Winter Bibs arrived in the mail. It was 38 degrees with strong winds. I went for a short 45 minute ride. I am impressed how much warmer these tights are versus my old Assos wintergarb. The foam insert was comfortable and combined with the front panel protection, kept this area warm.
I did not give these bibs a five star rating only because they are cut low in the midriff. I feel that they would be five star if they protected your stomach area better.
I rated them pricey, as of course, all Assos is expensive.
The fit & fabric are premium which results in warmth without restriction throughout. Good wind blockage also. Comfortable down to freezing temps although had to cover them with a shell just a few times throughout the winter, probably when I should not have been riding anyway.