She did look a little dumpy in X, but thats just in comparison to X-2. In X-2 her costume is extremely fitted/not-there-at-all. The fanboys thing, as they said ^

But although her X-2 costume didnt' leave much to the imagination, her X costume was unflattering I thought. Didn't like it much at all. I mean, Rikku in X was still marginally more clothed than in X-2, and she looked great in both.

Also can't stand the way Yuna moved in X. Whats with the little penguin-steps!? Nope, not cute at all.