What cons and pros are there to having knitted ugg boots?

I want to get a knitted pair of uggs for Christmas but i'm worried about them getting ruined by the snow. I also hear they get worn out quickly. If you guys could write a review on what you think about them or any experience you've had with them that would help a lot! oh, and i also already have a pair of original uggs so i don't want another pair of thoose.