After seeing the other reviews on here, I was a little worried. After a plethora of strange and slightly difficult dining experiences in Vegas, we weren't sure we had another one in us.
We went ahead and made a reservation for RA one night because it was close to our hotel. We were greeted by several hostesses and by the manager when we walked in. A little before 7, it wasn't crowded at all which was great. Our server was super friendly and engaging.
The food was really good. Highly recommend the Viva Las Vegas roll like other users have. We also had a Rainbow Roll and some Yellowtail Sashimi...all of which were great. RA is a moderately upscale sushi chain so their prices aren't too high but they're also not as low as your local neighborhood sushi place might be.
It's not really place I would recommend going to if you want to sit down and catch up with people. At the risk of aging myself...the music is pretty loud and it's hard to hear. It has a very cool, modern vibe though. It would be a great place to sit in the bar and have a few drinks and rolls at, and they do have happy hour!
Definitely recommend making a reservation (you can use OpenTable) if you're going on a weekend or during the holidays like we did. By the time we left (around 8), the place was totally full, so it definitely gets busy.