I think it's a great mechanic. The Civ IV specialist system was confusing as hell.
I'm also wondering whether specialist will be stuck in the building once you assign them to it. There is more of an emphasis on middle/long term planning and removing the slider from the game so you can't instantly swap from research to gold isn't that effective if you can still switch your specialists around with abandon. Leaves some interesting questions though as to what happens if the city is in starvation or if a mechanism like Civ4 slavery is still in the game. Although in the last case you could just say that you can slave away the peasants but not the middle class.