I've got a Dyson and two cats, one of whom has medium-long black hair which is very good at covering pale carpets. The Dyson seems to get most of the hair out, although I have to go over the worst bits a couple of times slowly, and occasionally I have to resort to pulling clumps of black hair out manually (out of the carpet, not out of the cat, however tempting it is). You can also get a pet hair tool with a beater bar to go on the end of the hose for upright models; this is useful for getting hair out of upholstery and stair carpets, and generally getting to awkward places that need a brush as well as suction.

I haven't tried hoovering up their hair with any other vacuum cleaner, though, so I can't compare the Dyson's performance to anything else.