Unquestionably, this is the BEST sushi restaurant you will find in the Las Vegas area. Chef Hiro takes great pride in his craft, and it shows in his cuisine. The focus is more traditional Japanese cuisine than fusion elements (I.e. nigiri and maki vs some "I love my ass" role you'll find at ayce establishments), however you'll still be able to get the latter as desired.
It is important to note that Tokyo Boys is not AYCE, and as such you'll spend more here. In return, you'll get a right & proper meal. The fish is fresh and never frozen, and much of it arrives the same day from Japan via Honolulu (they use the same suppliers as many of the $$$$ sushi establishments on the Strip). I suspect that the (very few) negative reviewers don't take this into account, and may not have a true appreciation for the genuine article. Their loss.
Overall, Tokyo Boys is a true gem in the Las Vegas valley. That it's housed in a former 50s diner just adds to its charm. Give Hiro and his crew a try. You'll love them.