This is from the same team that made 2012 - about the Olympics. All written by John Morton who wrote People Like Us for Radio 4 which is what led to 2012 and then WIA.
Many people have called this a satire about the BBC. It isn't. It's a farce - and not about the BBC either but about the PR industry and the awful managerialist language you get in all modern corporations.
The other thing is this: it's not as funny as it thinks it is. I got very tired of the BBC waffling about what good sports they are allowing a comedy like this to be made on their promises. But really, this is NOT biting satire - it is (very) mild satire at best, but mostly farce. It's basically harmless and toothless, and not satire at all then. A real satire of the BBC (in books such as Rasmus) offends its target - and W1A is basically a harmless TV documentary spoof.
Having said all that, the use of language by the writer is exquisite in its rhythms (though some characters can get wearing). There is a real musicality and bounce to the language - as though words were ping pong balls being shot back and forth in meetings by managers who speak managerialese to try and justify their absurd job titles and huge salaries. That really IS like the BBC.
So 3.5 rounded up to 4. It was a good choice to limit each series to 4 parts. That means it stops before it could really get annoying.
Worth a watch anyway. But nowhere near as funny as it (or the BBC) thinks it is.