So I've been hearing a lot of "But what's Torchwood about?"
From people who are watching it.
Over the series, it's flowed much more like an anthology series with some common characters than a traditional drama. It's Friday the 13th, The Series in Cardiff, only instead of an antique shop of cursed items scattered around town, it's a space-time rift.
The reason for Torchwood in Cardiff is a space-time rift that keeps spitting out strange things, new and different strange things. This allows (if not encourages) variety in story concepts, and all that's tying things together are the characters. Throw in "twist" plots (like "<schnip>" and "<schnip>") and it gets more erratic. It's the nature of the premise.