All four varieties of the Canon 70-200mm "L" zoom are renowned for being ultra-sharp.  This is the f/2.8 non-IS version, which for some reason doesn't seem to be widely available in the UK.  It's slightly shorter and lighter (and cheaper!) than the f/2.8 IS version, and sharper too, especially at the long end of its range.  If you're shooting moving subjects then IS isn't much of a help, and in that situation this is the best of the 70-200mm variants.

This lens can be used very well with a Canon Extender (teleconverter).  The 1.4x Extender makes it a 100-280mm f/4 zoom, and the 2x Extender makes it a 140-400mm f/5.6 zoom.  With either Extender, the lens will still autofocus on all EOS cameras.