I think Cosima feels like she's being held back because she's unwilling to let herself get caught up in the drama of what's going on. Right now she's more interested in putting the moves on her moniter.
Well considering the pace of the story, she's being left behind. When we first met this clone, I thought she was interesting, kind of the nerdy one of the bunch. The only problem is we've gotten so much story with the other clones that the Cosima side feels like a standstill ever since she went to Minnesota. I do think it's interesting that she might go with Dr. Leake (And maybe even turn against the clones, as this episode might have suggested) but again, the pace of the story makes her part probably the weakest so far.
For what it's worth, I feel your comparisons of this show to Who are a tad unfair. One show is aimed at a wide audience and one is pretty adult. As for the finale feeling incomplete, well this is the first time I think that the finale was just set up for a special. So yes it may feel incomplete, but that's because it was being used to set up story elements that will be fully explored in the fiftieth anniversary special.
Maybe it is, but the shows are on back to back. I don't mind that they were setting up for the 50th anniversary show, but it seemed like there were scenes in the finale that needed more exposition, or at least more development. As I said in the review thread, I do feel like this episode could have easily been a two parter and been so much better because of it. It's one thing to set up the anniversary show, but they also have to end the season that started last fall. Also, considering I'm not that excited for this special (For reasons being as far as I know the show has only been on for 8, but I do respect the long time fans of it
) all I cared about at the moment was them ending the season. It feels like more could have been done. I think the problem I had with this half of the season was the lack of development, both in stories and in characters. It showed greatly in the finale.