Cochrane is very good at what they do. This kind of systematic review is the highest standard of evidence when it comes to medical research. It's worth checking out some of their other reviews:

http://www.cochrane.org/cochrane-reviews/top

Note that these are abstracts of the full reviews (which they charge for access).

On a side note, meta-research deserves more funding!

http://blog.givewell.org/2013/06/06/meta-research-update/

edit: I linked to the wrong review before (not the one under discussion), so I edited that out. As gwern mentions in another comment, the link is broken in the BBC article. nairteashop found a different news release which seems to be the right link:

http://www.cochrane.org/features/tamiflu-relenza-how-effecti...