Breathable, not overheating
I have worn these with both mountain and road bike setups with good results. The Nordic AV is breathable and wind stopping, but not heavily insulated. I've still experienced chilly toes during rides around freezing (that said, my toes are always the first part of my body to get cold, regardless of footwear.) The cleat cutout is a generous size, and I was surprised how well it fit over my cleated mountain bike shoes, and even stood up well to hiking through some of the steep stuff.
I consider this shoe cover ideal for temps in the 35-50 degree range. At colder temps it might stave off frostbite, but there are warmer booties out there. But for a shoe cover you won't find yourself tearing off as soon as the sun crests the ridgeline, this would be a great choice.