I really enjoyed the Sinister arc, but found the following ones a bit less exciting. However, the last two issues have been much fun again, mostly due to Unit shaping up to become one of the best villains Marvel gave us in a long time. He's such a magnificient bastard; well-mannered, manipulative, and utterly psychotic. In fact, he's reminding me of a robot Hannibal Lecter.
I can't wait to see what he's up to now that the Phoenix made a return. And according to the previews, we're also going to see more of Sinister in the near future. Those two interacting would have the potential to be hilariously insane.