This weekend I finished reading the "Emperor Joker" hardcover. First off, I'm mainly Marvel as I tend to find DC to be kind of cartoony and otherworldy compared to the more "realistic" feel of Marvel. Anyway, I thought it was a decent read, though a bit confusing at times (as I find many DC titles if you aren't well-versed in DC mythos). I did enjoy the wackiness of it all and the many humorous elements, reflecting the plot of the Joker as emperor of all creation. I also found the pitting of the Joker against Superman to be a nice change up; Batman takes a backseat for much of the story until the end when he does come back with a boom. Either way, it was interesting to see the Boy Scout, nice guy persona of Superman battling against the chaos and insanity of the Joker. Again, I don't read a lot of DC, but from what I know of Superman, it seems a change of pace for him to deal with someone with like the Joker, who is so completely unhinged yet at the same time often more sane than everyone else.
Overall, I would recommend this title for more of a fun read than anything. Good for a laugh or two.