Great work. Your CPL (polarizing filter) has allowed you to pull out more saturation and contrast in your colors. I notice it particularly in your blues and greens. The changes are subtle, but they are noticeable nonetheless.
I do have a few comments to make about this photograph though. For starters, your white balance seems to be a little too blue. You might have done this intentionally, but I wanted you to be aware of the importance of proper white balancing. As the day changes from day to night, the color and temperature of light changes. Color temperature is measured in Kelvins with indoor light measured at about 3200K and outdoor light measured at 5600K. Indoor light is warmer and has an orange hue to it, while outdoor light is cooler and has a bluer hue to it. You can learn more about color temperature by watching the following video here. Even though the video is directed towards filmmakers, the ideas are the same for photographers as well.
http://www.youtube.com/watch?v=mwqNRqDx680&feature=PlayList&p=A971E46C3FB165AC&index=2
Also, it’s beneficial as you work through the assignments to carry your composition, technical and artistic ideas forward with each assignment. You’ve mentioned you didn’t pay attention to composition for this image and just wanted to see the effect of your filter, but it’s wise to approach each lesson with the information from the previous lessons in mind.
I hope you’re well and I look forward to seeing your next assignment!