the right lense. I have the 17mm-85mm IS USM lense which works well, but doesn't have quite as much magnification as I would like. It does have a good wide angle ability. I will be getting the 70mm-200mm/2.8L IS USM lense for the longer shots.
It shoots great pics with good light, and produces a full spread of light shades on the histogram in all the conditions I've been in so far. It also does well in low light if you crank up the ISO. It shoots as fast as you want, and has virtually no turn on lag. You will need an external flash since long lenses can throw shadows with the built in flash.
In short, I am VERY pleased with it. It is SO NICE to be able to hit the shutter a second time when a better picture suddenly presents itself. In burst mode, I got 7 full resolution jpegs of a baby Orca (8 days old) coming up for air with a little jump 'out' of the water.