Yes and no. My take is that Stern personally was a part of a complete re-orientation in strategic direction comparable only to Wilhelm at HERE, towards industrial organizing for density in an economic sector, by achievable means through a mixture of organizing agreements and traditional NLRB contested elections, which was immensely important. To speak directly to his individual work as an administrator, I think he did a remarkable job building a huge machine that all chugs in one direction, to that end, and has results to show for all that.
But I also think Woodruff has much more to do with the organizing successes themselves. And in contrast to Wilhelm & HERE, Stern could never quite leave himself and his various daft ideas out of the equation. Over the years its become increasingly clear that, whatever success he's had administrating the organizing juggernaut, he has brought may horrible ideas into the mix without sanction from the membership or appreciable benefit for them. it's one thing to strike a hard bargain for organizing rights with a stronger foe, or make such a bargain a system-wide strategy; it's quite another to just randomly say to a reporter from the NYT mag that 'maybe we're not so against school vouchers/ soc security privatization / widespread outsourcing', etc. Because as it happens the union IS against those things, and derives no benefit from Stern flirting with the opposite, and at the end of the day has no real force pulling it that far in that direction other than his personal kooky ideas about futurist triangulation.
If you could hear the absolutely idiotic ideas he and Burger seem to have for making seiu more like myspace, and less like a union, you'd be baffled (as I sometimes am) that he ever succeeded as much as he did as what he did. Maybe seiu needed someone as out of the box as him to thrive and grow enough to change the whole labor debate in the absence of a pragmatic and successful left intervention strategy. But regardless, the good parts about the organizing program are up and running now, while he does nothing but hurt the overall union with his idiocy these days. Plus, the failure in leadership manifest in a union prez blogging about china on huffington post while a perfect storm of problems goes down for his union (i.e. the CNA and UHW feuds blowing up at the same time) is enormous. He's never been held to account for that failure, like he's never been held to account for saying fucked up stuff to any reporter who will listen to him, or writing bullshit in his 'book'. The problems in seiu are totally real, my defenses of its (quite important) organizing successes aside.
This type of stuff really does drift overly into inside-baseball type trivia at some point though.