Not sure if there's any way to explain without "spoiling"...
They've destroyed the team.
They've destroyed the Hub.
There's nothing left of "Torchwood" at all.
Too bleak, too dark...I know the Brits are fond of killing off characters, but the characters are what got us involved to begin with, and to have to go through that many "deaths" is just too much chain-yanking.
Also, there's one major "plot flaw" in this scenario that was never addressed: Torchwood's main premise was that they were there to "maintain" The Rift (keep it closed!), and to catch/contain what slipped through it. The main "control valve" for The Rift was in The Hub, and, well...they blew it up! So when they blew up The Hub, did The Rift open up? Are all sorts of beasties and aliens now free to come on through? Nobody even MENTIONED The Rift through this whole thing!