Totally underrated. On the pricier side, but IMO totally worth it. You know you're in for a special Mexican meal when the complimentary chips w/3 salsas and 3 seasoning salts show up. And don't forget to ask for the secret 4th salsa which is an orange-yellow habanero-based salsa (different than the dark-brown Border Grill version which is awesome as well.) Packs a punch, and I can usually handle a lot spice.
Diego's Carne Asada is a huge boneless rib-eye, perfectly cooked and way more tender sliced up and put into corn tortillas than you think. You WILL be full when you leave here.
I expected the massive tequila selection to be more expensive than it was. I was able to find a few great tequilas for under $10 each.
The Chicken Molé is incredible and doesn't taste 'chickeny'. The molé is as good as the best I've had. And like the Carne Asada, it's perfect for slicing into corn tortillas.
It is a relatively long walk from the parking valet - all the way through the casino and down the long hall. But you will appreciate the return trip - walking off your huge meal will feel necessary.
Probably my favorite 'fancy' Mexican in Vegas. Doesn't get much better than this in this category. I know, 'fancy' and 'Mexican food' are sort of oxymoronic, but if anybody can pull it off, Diego can. Delicious stuff.