Pat Gillick strikes me as both an odd, and a weak, choice. Pat Gillick? Really? He's the modern GM worth enshrining? It sure seems to me that if he's HOF-worthy, then there must be ten other GMs who are worthy.
I do think that it's time that GMs are added to the Hall; their role in the game for the last forty years or so is probably far more important as what managers do, and managers seem to go in at about the same rate they did when managers were far more responsible for personnel choices. Gillick, though, strikes me as sort of like a Rollie Fingers selection -- yeah, modern relief pitchers should be in, and yeah, Fingers was awful good and not a terrible HOF choice, but he's going to be the worst HOF reliever for a long time.
By the way, the Pat Gillick bullpen page is outstanding.
Now, I think Gillick deserves nothing but kudos for his work in Toronto. Of all the expansion teams, Toronto might well be the model one; although five terrible "expansion team" years is below average, they were decent in year six and then a contender for the next decade.
On the other hand...the one thing that was notable in his later career was his ability to walk away from disaster. The year after he left Toronto the Jays finished 56-88, and they were bad the next two years, too. The Orioles slipped under .500 in his final year, and they haven't reached .500 since. The Mariners were good all four years he was there; the next year, they went 63-99, and then had two more lousy year. Obviously, Gillick can't be blame for what the Orioles did ten years later, but his record looks a lot less impressive if you give him at least part of the blame for the next 1-3 years.
To be fair, the Phillies haven't suffered at all after his stint there.
I'm not really saying that he's a mistake; he just seems a little weak to me. But again, I'm glad that modern GMs are going to start going into the Hall, and you have to start somewhere, I guess.