I only saw series 1 when it aired back in my early-mid teens. It used to creep me out.
Just been re-watching it this week.
Series 1 is fantastic and most of series 2 but towards the end it starts to feel like a sit-com. Starting 3 as I type. I just wasn't expecting them to flesh out the characters beyond sketches.
edit:
I'm also not alone in feeling that some of Little Britain sketches must have been influenced by the show. Particularly the Job Centre/Weight Watchers.
http://www.imdb.com/title/tt0184135/...8?ref_=tt_bd_3