If they are asking you to "comment" on the efficiency of the recrystallization process, they are probably looking for comments in general terms rather than in mathematical terms. So how clean was your crude product compared to your crystallized product? How much of your product was left behind in the mother liquor? How much time/solvent/heat/other resources were required in comparison to other methods you may have used? These are all different ways to think about efficiency. You can attach some numbers to a few of these if you were able to measure them, such as purity of crude and final products, and loss of material during recrystallization (if you went back and measured the remaining product in your mother liquor), others you can make some educated guesses about.