The first inclination we had that anything was happening was when Elektra turned out to be a Skrull. Then it was a matter of "Who else?" But before we forget her completely, Mighty Avengers 16 gives us insight into her abduction.
Going all the way back to New Avengers #1, we see a pivotal scene from that series played out from a different perspective. We finally see who was orchestrating the whole Raft breakout. It's an interesting twist, but not mind-blowing.
Then we see Elektra's abduction. I'll have to say this for her, she puts up a good fight. Going against several Skrulls with various superpowers, she manages to take a few down before it's over. Of course, she loses and gets replaced.
The biggest problem I have with Mighty Avengers and New Avengers since the Invasion started is how Marvel is using both titles as sort of a "backstory dump". The stories no longer flow from issue to issue, but end abruptly and then pick up with an entirely new story the next issue. For example, this issue ends with "Next Month: The Truth About Hank Pym". I know the main storyline is happening in the Secret Invasion title, but perhaps Marvel should have come out with a second miniseries (like the "Secret Invasion: Who Do You Trust?" one shot they had), perhaps called Secret Invasion: Abductions and used that as the story dump. As I've said in previous posts, I'm no fan of DC's "miniseries from a miniseries" approach to Final Crisis, but at least Marvel is telling a linear story in Secret Invasion. This would have been a good use of that second miniseries concept (as long as they didn't go overboard like DC has with no less than four different miniseries coming out of Final Crisis while it's still going on).
Two months ago in New Avengers, the story ended with Spider-Man and Ka-Zar in the Savage Land suddenly being attacked by Captain America (most likely a Skrull, but still...). The next month, it was a completely different story and we're still waiting to see what happened in that fight. It's getting a little frustrating.
But since this is what we're stuck with and we might as well get over it and move on, I'll have to say it is interesting to see what all had to go on behind the scenes to make this invasion happen. For the most part, this is good storytelling.
But again I have to ask: Where are the heroes who have been replaced?