A Well Crafted Beginning
"First Strike" is a great jumping on point for the X-Men and New Mutants. The X-Men are finally coming back together and the New Mutants are just back from their quick trip to Madripoor. The teams are living together and the reader can get a good sense of what is happening for each team. You don't need back-stories out the butt to understand what is going on. (Granted, a cursory knowledge of Cameron Hodge and the X-Men's dealings with Genosha in the past will come in handy with this arc, but I'm just talking about this issue.)
As to the story, the butting of heads between the two teams is perfect. The mansion is home to both the New Mutants and X-Men, but things are a little dicey now that the X-Men are actually back (and the upstairs no longer exists). Even more compelling is the leader of the assault on the X-teams: Havok. If nothing else compels you to read this arc, the brother of Cyclops (a mutant himself) is working for Genosha. And that's pretty much where this issue leaves you. You get the background and the ending of the book leaves you ready for the next part of the story. Nicely done.