I think SG-1 is running out of juice. their first major mistake was to promote richard dean anderson for BG, thereby pretty much dissolving SG-1. Notice the lack of missions through the stargate this season? The whole plot line has changed, and they've basically started anew.
Also, putting carter in charge of SG-1 was a mistake. She's smart and a great scientist and all, but not a leader. Sorry, just how it is. If they really wanted a female in charge of the group they shoulda gone with some new chick. ALthough, I like how carter isn't one of those"i have to prove i'm as good as or better than any man in every way" characters. At least, not anymore.
I just feel like this series is slipping and will continue to do so.