In the former location of Japponais, Otoro has a nice vibe just off the casino floor and adjacent to the Mirage conservatory. Its a nice blend of trendy/energy but could also be romantic. There are two distinctly different rooms, the bar/lounge with robata grill and the dining room.
We sat in the bar/lounge and ordered wine and a bunch of sushi/robata. The food was good, I especially liked the Tiger Roll and sashimi/nigiri lives up to LV strip quality and freshness.
Unfortunately the service left a bit to be desired. Our waitress, Dana, was having an off night. The wine arrived after the first course was finished and there were several botched orders that were wrong /completely missing or had to be reordered. Oops.
Despite the poor service experience, I would go back as I doubt this is representative of the restaurant. I would give it one more try!