Si Spencer comes up with a delightful premise: what if someone experimented with the demon blood in Constantine's veins? The result is a great new take on demons rising in London. 
 Besides just having a great premise, Spencer's writing is also strong. It nicely moves along, revealing things as it goes, but also does a great job of highlighting the characters -- especially Constantine and his nurse Friday. I'm also impressed by his grotesqueries. Though Spencer goes for the splatter, it's disturbing, rather than being funny as was the case in Ennis' notably gory run. 
 Overall, a nice Hellblazer arc. I'm sorry that Spencer didn't get to be a regular author for the book.