I've bulk-watched this in iPlayer over the last couple of days and have to say I've actually quite enjoyed it a lot. It is very funny in places and I quite like a lot of the jokes. Joyful's one-liners are particularly good.
Have to agree about the one-hour opener: the half-hours are much better and the first episode is, unfortunately, not as good as the subsequent half-hours so that might have turned people off. I don't really understand this 'new' fangled 'opening hour' episodes -- it doesn't sit well with me; kind of like admitting it's not quite sitcom by giving it a comedy drama type slot. (I disagree with Mark's suggestion that it is comedy-drama, as it's sitcom to me, though he did write that after episode 1, so I'll let him off!) It never worked for me with Pulling, Krod Mandoon and, if I recall correctly (though I was only half paying attention), Jam & Jerusalem just put in a blatant 'This is part 2!' screen and effectively started a new episode at 8:30pm on Sunday nights. Well done, Jen! Here's hoping Benidorm does the same.
Anyway, that said, Taking The Flak all good. Not the best sitcom of the year, but good enough to keep watching and enough to warrant a series two.
Dan