Awesome Story All Around
I got a kick out of reading this issue. Supergirl and Powergirl work so well together, all while fighting an underwater psycho home security system. It really feels like they are evenly matched because the fortress knows how to handle a fight against Kryptonians. The action is all awesome, especially seeing the two heroes work together, but the humor really steals the show.
This worked really well as a single issue, because it's ok if you hadn't read the previous issue and the conclusion is solid enough not to leave you up at night wondering what happens next (though I'm sure it will be big).