Eh, I haven't seen a single story of his that wasn't utterly forgettable, especially his Detective stuff.
... Really??? Not even the issue with Robin and the Joker on Christmas? That issue single-handedly joins the ranks of the all-time great Joker stories! This essay puts it better than I ever could: http://lovedatjoker.livejournal.com/29049.html
COUNTDOWN, I give him a pass on, because A.) it was clearly editorially dictated from the start as Dan DiDio's dream version of what 52 (which he hated) *should* have been, and B.) wasn't Sean McKeever the actual scripter? Dini was a hired gun for something that was clearly a piece of crap from the start.
And I firmly disagree with your assessment that Harvey's dualism is tired and old, simply on the basis that it actually hasn't really been explored enough. Writers are usually more content to reduce him to a gimmicky-supervillain than really delve into the complex meat of the character. Tomasi is an exception, and until Harvey went all Silver Age supervillian-with-a-blimp-and-death-pennies, his depiction of Harvey was refreshing but still totally in keeping with the character before. But this? I mean, I'll see if they can actually come up with a proper story to justify this, but my gut says this is NOT the proper direction to be going in from the groundwork lain by Tomasi's story.
And when did Dini retcon Jervis into being a pedophile? Frankly, that's sadly been his canon character ever since Morrison's ARKHAM ASYLUM, all the way through Jeph Loeb's stories. Dini's Hatter story was, as I recall, the first time in a LONG while that Jervis wasn't a pedophile (or a hat-fucker, as in SECRET SIX), but more like his more-awesome animated series counterpart!
As for the Catwoman-heart thing, that was a moment of total stupidity that was utterly redeemed by the ending of the story where she totally, gloriously, magnificently, and brilliantly pwned Hush. Most people who hated the heart thing were, I recall, won over by that ending, and forgave Dini, simply because it was so well executed.