Canon's "normal" 50mm macro lens. A very sharp lens. On its own this lens goes to 1:2 (1/2 life size). To reach 1:1 it requires the addition of the life size converter EF, which significantly increases the total cost (from around $240 for the 50/2.5 to around $480 for the lens and lifesize converter).

The Canon EF 100/2.8 USM Macro goes to 1:1 without additional optics and costs less (around $430), so if you need 1:1, the 100/2.8 macro is certainly worth considering.

If you want a smaller, lighter, cheaper lens and don't mind 1:2 magnification, then the Canon EF 50/2.5 Macro is definately a good buy.