Spencer seemed to have a lot of fun writing Hydra Steve, as others have noted. I think his take on Civil War 2 is the only good stuff to come out of that event, since we got to see some Cap Keikaku.
But once it became an "EVENT" it went off the rails, mostly because they kept pussyfooting around Steve being a Nazi and because Spencer clearly just got burnt out by the scale of the event. Captain America as a Hydra agent is twisted because he should actually be good at being evil. He should make the right points, effective at establishing himself, and be seductive in explaining his views. That's the very real danger you could be playing with -- someone so fundamental "good" bringing all those wonderful qualities over to the side of "Evil." And early on, when Steve was sabotaging the Red Skull, it seemed to play into that, which is what made those few issues a lot of fun.
But then, once he became the Ruler of the Earth, Hydra Steve suddenly started doubting himself and kept botching his execution. He became a hackneyed villain instead of a credible, seductive threat, and that cost the book a whole lot. It became really uninspired, and Spencer seemed miserable writing it, which really didn't help him at all, even if he slipped in a few gems like Pymtron and the "Twitter" stinger. He should've kept it confined to the Captain America comics, but as is, he bit off more than he could chew and totally botched whatever good he had instilled in those early Cap stories.