It seem to be the consensus that Dini's recent (last five years) work has been passable to poor with the exception of his Joker issue of Detective - that's really the only one that stands out in the run. Don't get me wrong, his run isn't bad and certainly worth reading if you're a fan of Dini or Batman, it just isn't interesting enough to revisit once you have read it.
Countdown is probably the worst comic DC has put out in a long, long time and the fact that Dini masterminded the plot and singlehandedly wrote one of the worst issues (#23, where Superman-Prime tortures Mr Mxyzptlk and Earth-3 Zatanna for the entire issue) looks bad on his report card. It's not so much the editorial mandates (because there were not many, and none regarding Jason Todd) that made Countdown so bad as the various inconsistensies between issues - one issue would end in one way and continue in a wholly different way. One that springs to mind immediately is the one where Flash says "You deserve to die" and seemingly attacks Trickster and Piper, which is never referenced again. (http://www.funnybookbabylon.com/wp-content/uploads/2007/09/wallysasociopath.jpg) This is why I blame Dini - if you are the head writer, you're supposed to make these things work. The people writing did a bad job, and Dini was in charge of the people writing which means he did a bad job. Re:Mirage - first three issues were good but then the series lost it and went down to "ok". I will admit that Sirens #3 was better than the first two issues, and if he can keep this up then he might have a hit - Streets of Gotham is still nothing special though.
My last gripe is just a pet peeve and not a complaint about the actual writing, but I'm getting really tired of Zatanna. It's great that you love your wife Paul, but she doesn't have to be in every issue of every comic you write! Gosh!
Just like you seem to have limited exposure to Dini's bad work, I think stig is less familiar with his cartoon work. I only rank Dini as a mid-tier writer because however good his DCAU work is, his comics work over the last five years is only decent at best.