I watched it. Not very good at all. Let me count the ways....

1) The entire "CIA arresting Five-Zero" plotline was lame and came out of nowhere, to the point where it seemed like we missed some important scenes between the Five-Zero episode and the start of the Magnum episode.

2) No McGarrett, no Danno, no Grover, no Adam. They must have had some contractual issues with those four actors, so they weren't in the show. That's why the CIA thing was (poorly) written into the episode, explaining their absence. Dumb. We were left with Tani, Quinn, Junior (who was barely seen because he was held hostage the entire time), and a cameo by Kamekona. Why even bother?

3) The whole episode was sloppy and pointless. There wasn't enough material for a second episode. They could have done a much better job with this crossover. They pretty much ran out of plot after the Five-Zero episode.

I also found it weird that they chose to develop the Tani/Junior romantic relationship on the Magnum crossover episode. But they didn't kiss yet, soooo... I guess that's still forthcoming.