It's interesting to reflect that the original run of Doctor Who killed off two regular characters in its third season, and then of course changed the lead actor in the fourth; there may be a natural time limit to these things (unless you are Tom Baker). It's been a grim old time all round in Who and its spinoffs, what with Kylie being killed off in Voyage of the Damned as well.
This has been a much better season than the first one. The writing has been better, the central concepts better, the actors seemed more in their roles (again, a huge contrast between tonight's episode and End of Days). The only episode that didn't work especially well for me was Out of the Rain, the one with the circus troup materialising from ancient film records. (And my second least favourite was Fragments, which had the same director, Jonathan Fox Bassett.) I enjoyed pretty much all of the others.
Both Adam and Something Borrowed leant to an extent on Buffy episodes (obviously, Superstar and Hell's Bells); in the former case, honours are about even, in the latter case, Torchwood did it far better. An even more obvious borrowing from Buffy was James Marsters, who sets alight every scene he is in. The other recurrent guest star was Freema Agyeman reprising Martha Jones from last year's Doctor Who; she sparkled without dominating, which is fine. And Richard Briers in A Day In The Death was fantastic.
Adrift, for obvious reasons, was the episode that hit closest to home for me emotionally. Apart from that, I really liked the fact that a bit more care seemed to have gone into constructing the Owen/Tosh, Gwen/Rhys[/Andy], Jack/Ianto[/John][/Gray] character arcs; particularly the first of these, where there were several episodes showing this relationship as one which was changing and developing (Adam, Dead Man Walking, and of course Exit Wounds). A fan who had only seen the second series would find it rather difficult to believe that Gwen had ever had a fling with Owen; let alone that Ianto had his girlfriend hidden in the basement.
Anyway, I liked most of the first series of Torchwood (apart from the very last episode), yet felt the need to be apologetic about it at the time; I don't feel anything like as apologetic about liking the second series.
(Various other people have done their reaction posts while I've been writing this. I would particularly recommend calapine, here. Though the comment threads here get amusing too.)
Anyway, roll on tomorrow at 1920 our time, 1820 for you in the UK and Ireland!