Light Speed 1/2 Zip long sleeve running tops are great for cold weather running. Everyone is different but I will switch from Aero LS tops to Light Speed once the temperature drops under 12 degrees.
Light Speed has the thumb holes so you can get better coverage of your hands to keep them a bit warmer. You can still fit running gloves over the top when desired.
After you've warmed up on longer runs the 1/2 zip is great to open up and let some torso heat out to stay closer to your optimum body temperature.
Sizewise it's not too bad. Most runners are fairly slim so I feel confident in saying if the top fits your shoulders and is long enough, it will likely be a bit baggy in the arms and around the torso, but hey that might just be my body shape.
Overall I love the Light Speed, I have three of them and it's the second season I have refreshed my set for child weather running.