Thorn has very good points. It's a fine distance, but riding that far every day is quite a drain on your energy unless you've already been riding regularly. It may sound a lot shorter than a long weekend ride, but you don't get days to recuperate. Going out to ride twice a day no matter the weather is also more of a challenge for your mind. And you get to do it all over the next day.
Take your time, increase gently and let your body get used to it, and don't be discouraged if you suddenly feel very slow, or need a day or three off. It's terrific exercise and a great way to start and end your work day. I'm sure you'll find yourself completely addicted 
There's a ton of good info here for commuters, and feel free to ask any questions at all.
Winter riding is much less about badassery and much more about bundle-uppery. - malkin
1995 Kona Cinder Cone commuterFrankenbike/Selle Italia SLR Lady Gel Flow
2008 white Nakamura Summit Custom mtb/Terry Falcon X
2000 Schwinn Fastback Comp road bike/Specialized Jett