I own the Canon 100mm macro, which is an awesome lens. But it's heavy and hard to hold steady. I don't use a tripod because I'm constantly lying down, standing up and leaning over objects to take take photos of flowers and insects. So, when the 60mm was introduced, I knew immediately that I wanted it, given that it's about half the size and weight of the 100mm.
The 60mm is wonderful! Not only is it light enough that I can operate my 300D with one hand, it's comparable in quality to the 100mm. It's truly a fun lens to use. Great for portrait work as well as macro, and performs excwptionally as a general purpose walk-around. USM is nearly silent. I'm thrilled with this lens!