These shoe covers worked really well to keep my toes warm, over my regular road shoes, down into the 30's.  I've used them several times for about 90m each time and they do the job.  Some quick notes, they are BRIGHT yellow.  I personally like this as I ride in traffic but they may be a bit much for some tastes.  Also, I've switched to actual winter riding boots, just too consistently cold to make these convenient, but plan on using these for surprise rain showers in the warmer months.