I really like to get out in the Winter, especially when it's a cold bright day. I've shot quite a lot recently with my 50mm f/1.4 over the Christmas break, which is an awesome lens in full frame on the Canon 5Dc, but yesterday when we wandered out I decided to go with the 100mm f/2.
Within photography circles, it's very much the unearthed lens in Canon's camp with the 85mm f/1.8 seemingly taking most of the plaudits for non-L lens owners. With a crop factor of 1.6 the 85mm rounds up to 135mm, making it the ideal portrait lens, and at full frame 85mm is an ideal length too. However, when I bought the 100mm f/2 it was ideal on a crop as it gave me that extra reach at 160mm on crop, and on full frame the images are just tack-sharp.
It certainly appears to be a pretty well kept secret, and at the price it's a great deal if you're looking for that ideal lens - whether that's for full frame or crop.
It made a nice change to get out and about yesterday, in dry clean air - I just need to find more places to get out and try the 100mm to really stretch itself further.