Enjoyment: Pretty fun! it would have been nice if the gameplay had tied into the opponents in some way. Perhaps some characters limiting you to certain operators or numbers, or adding negative numbers or fractions.
Creativity: I have to say, I feel like I have seen this kind of maths game before. Even so, the way you worked in the randomisation did introduce some new opportunities for strategising which I enjoyed.
Presentation: I like the art, but it clashes a bit with the super clean looking UI. Also I missed the first dialogue because I was still reading the "How to Play" LOL.