It's easy to see why people give Koi 2 star reviews, and easy to see why they give it 5. Some of the food was really really good - the miso black cod, while ripped off from Nobu, is still really great. The crispy rice topped with spicy tuna is really wonderful. I'd go with 4 stars for those, but I could see 5.
But, the Vegasness of Koi overpowers the food. Ridiculously loud club music that seems designed to make you want to leave ASAP. Servers who, likewise, appear to have a prime directive to get you in and out within an hour or even 45 minutes. And overall a velvet rope vibe that might be OK for a club but it off-putting for a restaurant.