Re Torchwood and Doctor Who: SPOILERS-ish.
Last season, Torchwood didn't have anything that ultimately tied everything together by the end of the thirteen episodes.
The three seasons of Doctor Who, on the other hand, have had threads that have run through each batch of thirteen. There are things that have been learned, which show up again later. Take, for instance, the first season of Doctor Who, where Rose went back in time and met her father in the story "Father's Day." It seemed like a stand-alone episode. But, suddenly, in the final episode of the season, "The Parting of the Ways," Rose told her mother of the events of the earlier episode, giving them as part of the reason for the decisions she was making, and convincing her mother to take action, as well. That final story drew upon other the stories told through the season, as well, creating a final, satisfying story from the whole.
Torchwood has yet to create that kind of story arc. The potential is there. And hopefully what we saw tonight will be part of what is to come.
And that makes for good television writing.