My two experiences of tasting 西湖醋鱼 in HangZhou were not bad at all.
The first time was in a "Xing-Qiao" Hotel (a three star hotel at the time), and the other time was in a good restaurant,(can not remember which one, but definitely not in 楼外楼).
We were served by a big fish at the first time. While at the second time, there were two medium sized fishes. We were happy with the quantity.
Although these things were passed by for years, I am still having a good impression of the good taste.
HangZhou is a good place.
Regards
?行?士