I recently read the first five issues.
It actually makes some kind of sense when read like that.
I like the artwork and the central premise of someone like Turpin being a portal through which Darkseid appears isn't a bad idea.
However, the comic is, I think, severely hampered by its pathetic attempt to be inclusive of the entire DC universe. EARTH X, which was ludicrously epic in size and extremely nerdy, referencing all manner of bizarre parts of continuity, didn't try to incorporate vast elements of the Marvel Universe in its fourteen issues, instead, saving a lot of it for its sequels. FINAL CRISIS, on the other hand, not only has the heroes of Earth, but the New Gods, the Green Lantern Corps, and the Monitors of the 52 universes. It's just unwieldy in its size.
I think it would've been better served if the Green Lantern Corps (who are overrated) were not involved - Green Lantern, fine, but the entire Corps is too much. The same for the Monitors. I like the idea that gravity and time are warped by the 'incursion' of Darkseid into the material realm, but... there's so many bizarre plot lines and inconsistent realities all screaming for space... some breathing room would be nice.