Does anyone else think this is quite a small bonus?
A normal tile improvement will give a 2-3 bonus itself, so the net bonus of this ability is 2 or max 3 extra yield.
This seems paltry compared to civ 4 (which gave the city I think +1hammer +6 science).
Whats more, you have to have a citizen working the tile (hence feeding it) whereas in civ4 the super citizen didnt need to be fed or use a population from the city to work.
I guess this depends on how costly science advances are.