i dont know who said this but i will repeat it. size is not always about superficiality. when i was dating, i would not go out with anyone who seemed big to me because i was VERY small and 1. i was just plain scared and 2. it was not (and still is not) something to which i was attracted. most of the dates i went on were NOT shiduchim, but the few dates that were, were all skinny.
i think it really depends who is asking and why. my standard answer when a guy asks me if a girl is pretty is i dont know what you consider pretty. i usually say go on one date and see for yourself.
also, many times attraction comes with time, so if everything else is great, as long as you dont abhor the other persons looks, i say give it another chance.
but thats just my opinion, and i certainly dont expect everyone to agree.