I don't know what to think of Geoff Johns these days. Back when he was mostly just writing Flash and Teen Titans and JSA, I thought his work was pretty top-notch. He had a good handle on characters and personalities (even if he did tend to alter those personalities early on--see: Kid Flash) and he was fantastic about weaving continuity into the story without being hampered by it. He made revamps and untangling continuity look easy--Hawkman's a particular case in point, but even just tying together the Hawkman mythos with Metamorpho and the Marvel Family was a stroke of brilliance.
At times, I think his work has been less spectacular. I used to blame it on him writing too many things at once (like when Teen Titans megasucked while he was writing Infinite Crisis), but now I can see that he's got a few quirks and idiosyncracies that keep cropping up in his work, whether or not they make sense. It's clear that he has an abounding love for the way comics were when he was growing up, a nostalgia that almost reaches Byrnian or Meltzerian levels. If his work ever had any subtlety--and I like to think it did, once--it almost completely lacks it now. He has a tendency to take things which were metaphors or symbolic and to state them as explicitly as possible; I didn't mind it when it was "yellow=fear and Green Lanterns have to be fearless!" or even the emotional spectrum, but when it's "hey, Rudy Jones is a parasite," it's a bit much. He's become the go-to guy for "rebirths" and "secret origins," even though "Flash: Rebirth" compares to "Green Lantern: Rebirth" or "Superman: Up, Up, and Away" about as favorably as "Spider-Man: Chapter One" did to "Man of Steel." His secret origin stories so far exist mostly to tie Johns' current storylines and status quos into the character's origin story, and to make it clear that the character has neither grown nor changed since his or her debut.
And the less said about his love for 1970s Superman--to the point of reintroducing Steve Lombard, writing comics that basically function as sequels to the Donner films, killing Pa Kent for no reason whatsoever, retconning Ella Lane into the grave, and turning newer characters like Ron Troupe and Cat Grant into one-dimensional caricatures which bear almost no resemblance to anything which has gone before--the better.
It's not all bad, mind you. I'm one of the few people around who actually enjoyed "Blackest Night" (except who was chosen as deputies for most of the Lantern Corps), and while I think "Brightest Day" is off to a not-so-good start, I'm intrigued enough by the concept to follow it for the time being. Several of his Superman arcs--the Legion and Bizarro World stories, for instance--have been pretty great, and I'm still fond of his older work. I just don't understand what could make someone so inconsistent? Is it because he's no longer particularly bound by editorial constraints? Is it because revamps allow him to freely pick and choose what continuity to acknowledge and ignore, rather than to just try to untangle things as he did before? Is it because he has a tendency to write books past the time that his ideas have run out? Is it because his quirks have magnified exponentially due to a lack of backlash from fans to keep him in check?
No, I'm pretty sure I've figured out the answer: the reason there are so many different levels of quality coming out under Geoff Johns' name is because there are many different Geoff Johnses. In fact, I'd venture so far as to say that we've never actually met the real Geoff Johns, only these duplicates of him. The real Johns is a writer of unbelievably great caliber, with Roy Thomas levels of continuity knowledge, and chances are he'll enter the picture almost immediately after I've revealed this information. Until now, the only Geoff Johns we've had have been these pale imitators, but soon we'll meet the original version--and tremble.