I love the look of Bing's live tile. But Bing isn't so accurate for my location ( N.England) and the tile isn't that live either. Oh and I hate that you can't have windspeed in mph, combined with temperature in centigrade.
The historical weather info is interesting though
I've tried a lot of different weather apps but always seem to crawl back to Nokia's Weather Channel app. I just like the way it's presented a little more, plus it is way more accurate than most of the others for my area. Live tile is nice too. Oh and it's free.