I can't tell you I'm fan of Kumi. I've been to many many sushi houses over the years -- the vast majority of which frankly are better than Kumi.
They bill themselves as having an imaginative sushi menu. The most imaginative item on the menu was the crispy pork roll that was served with coleslaw. It was tasty and it is a bit unusual but very pricey at $25 for what you get. Other than that there was nothing on this menu that was what I would consider "original" or unusual.
That theme follows through with the rest of their sushi /sashimi which was from a portion perspective small, and from a price perspective very high.
Nothing wrong with the quality -- it was pretty much the same as most sushi restaurants I've been to.
We were there at 9:30 or so on a Thursday night and it appears to me they were anxious to close, so the service left a lot to be desired.
Frankly if you want to find sushi in Las Vegas, there are many better alternatives. The small place at the very back of Harrahs - which although I can't remember the name -- was an outstanding value and considerably more imaginative then Kumi.
If you don't mind having your wallet vacuumed of money and leaving hungry then Kumi is the place for you!