Torchwood was more adolescent than adult. It tried to be adult, but did so simply by having swearing and lots of bed-hopping. It seemed to be as if it didn't know what adult really meant. Also, the show did not really have a focus.
Even in the campy old days of the 70s and 80s, Barry Letts, and Terrance Dicks, and the other producers would have a stock of the latest scientific journals on hand to ground the show in the latest theories (even if they were later disproven). Some of the ideas seem very simplistic now (plate tectonics shifting the continents was brand new when The Silurians was first aired).
The new show, esp lately, seems to have switched tracks to "The Doctor is a fairy-tale Wizard, and the sonic screw-driver is his magic wand". Yes, River even says words to that effect. It just seems to have lost it's driving life and energy. Stories don't even bother to be internally consistent anymore. The arcs seem very forced and shoe-horned in (even more than in RTD's time). I'd prefer 12 or even 6 really good stories with no arc to 15 meh or weak stories with a blah arc.
But that's just me.
I went through series 1-4 last month, and had a blast. Even the 4.5 specials (though Planet of the Doomed was missing from NetFlix for some reason. Oh, and I skipped Lover&Monsters and Fear Her.)