The 100mm F2.8L IS USM Macro is the first lens to feature Canon's 'Hybrid IS' system, that aims to improve stabilization at close focus distances by correcting for two types of shake movement (both angular and horizontal/vertical shift). Optically the lens is superb, autofocus is fast, silent and accurate, and it's well-built too (including weathersealing). The new IS system is one of the most effective we've seen, but don't expect a 'magic bullet' for hand-held closeups: for serious work you'll still need a tripod.