You know, I'm used to it as an American. All the American shows have about 23 - 26 episodes a season, and they go on several hiatus's, usually one near Christmas for a few weeks, and one near Easter for a few weeks. So it was a treat when I got to watch all 13 weeks of Who consecutively.
It doesn't kill a show. On the contrary, it makes it more anticipated.
Oh yeah. Isn't it annoying? I don't think it's really a BAD thing because of the above reason, but won't it keep us looking forward to it up til' it comes on again? When Series 5 came on last year I was at a friends house and I started screaming. I hadn't seen it in so long and I was thrilled. (friend thought I went insane)
It'll make you even more thrilled once it comes on! XD