Well, it'll be some years before this treatment becomes "productized", but it's still heartening. By the time it's been through the development process, I also expect they'll have the implant and shot on synchronized schedules, so you'll only have to go to the doctor 4 times a year instead of 7.
Obviously, it doesn't do anything for STDs, requires advance planning, and likely has a relatively large up-front cost compared to more casual methods like condoms. Therefore (warning: layperson's wild-ass speculation coming up), it probably won't much reduce the societal incidence of unwanted pregnancy --- most people would only use this as the primary contraceptive in the context of a long-term relationship, in which case they'd generally already be using something else if this weren't available. But, it will make couples' lives easier, reduce the pressure on women to be "the responsible one", and give men a near-foolproof veto on unwanted paternity, all of which are good things.
Also, female chemical contraceptives have always had unpleasant side effects for a significant minority of women, probably because a woman's hormonal cycle and reproductive apparatus are simply more complex than a man's. Extended studies will probably uncover side effects for some men, but I'm willing to bet it will be a smaller fraction, with less serious side effects on average, than for women on the Pill or Norplant.
My main question: why did it take so damn long? The treatment doesn't sound too terribly complex. Why did biologists figure out the Pill decades ago? Is the delay a product of social forces or scientific limitations?
UPDATE: New Scientist has further coverage, including the following:
But Anna Glasier, at Edinburgh University's Centre for Reproductive Biology, says it remains to be seen how acceptable couples find such treatment. She and her colleagues carried out an international survey of men and women's attitudes to male contraception.
"We found that the majority of men would prefer a pill [rather than injection or implant], but testosterone cannot currently be made in this form. So, I am not sure how successful the Australian treatment would be," she told New Scientist.
Odd. I can see the appeal of not having to go to the doctor, but the sheer convenience of only dealing with contraception four times a year seems really attractive to me.