The last episode of this finished half an hour ago. On the intellectual front, the five-episode arc worked very well, the story was good, the acting was excellent. For that last one kudos to Euros Lynn, who managed to let John Barrowman act very contained and Gareth David-Lloyd a bit more emotional. The female characters, all of them, were awesome. Strong, capable and still human.
Still, I have some issues with this series. First, of course, Ianto dying. It was a good death, a well acted scene, but it was purposeless. I had the hope that it would motivate Jack into action, which is an old movie trick. This never happened. On one hand, no cliché, on the other hand, death of a much-beloved character for no reason. I cried like a baby over him, because he was so awesome this series. Though most of the grief was for fanon!Ianto and the fear that fandom would react like it did. I'm having faith in the writers in fandom, that the AU's will be plentiful and fluffy.
Second issue is that there is talk of a fourth series. After the ending, with Jack leaving for the skies, this seems very unlikely. Torchwood has ended. Unless, of course, they set the next series in the past. Which would mean the return of Ianto Jones, which would make fandom very happy. We'll see if RTD survives the coming storm, first, shall we?
Third issue is Jack. We know he can be a bastard and has done some pretty bad things in the past. Killing his own grandson though is something I would never have thought he would do. Well acted, again, by Barrowman, but not the Jack we know and love. Leaving everything behind, leaving Gwen and everything he fought for, seems like the easy way out. He is running from his own actions, which won't work, because they'll always stay with him.
Fourth is, again, Ianto dying. For me it took out the emotional investment in the series. I watched the last episode with much less interest than the first four. I still had the hope, until the end, that some deus(doctor?) ex machina would return Ianto alive and whole. Unrealistic, probably, but it wouldn't be the first time, as others have noted. I think Ianto dying in the last episode would have let that episode have a bigger impact, for me.
As I said, we'll see if a fourth series happens. Which, according to the claims that if series three was a success, it would, should happen. I believe that the viewing figures were about five million in the UK alone. The totals should be way above that, so this can be called a success. Let's hope that Euros Lynn will still be directing, that the plot will be good and that the team will be complete once again.