I hate to rag on the fat, ugly kid in recess but Ah Sin really does deserve the low Yelp rating.
Service was subpar. Food wasn't great. I was in the mood for sushi and Ah Sin's disappointed. The only thing that felt good was the 7&7 I ordered after a long day of work.
On paper, the restaurant seems perfect: it's well-decorated, fancy-looking and in a perfect location for viewing the Bellagio's fountain. I guess something had to give and, unfortunately, it's the restaurant itself. Skip this place if you can.