It's a diner. I've been to 3 of the locations - all on Flamingo. The one on W Flamingo nearest the Strip looks more like a nice restaurant then a diner but the food is still diner delicious and the staff is exceptionally nice & accommodating.
The one on E Flamingo/Sandhill .. Food not as good & the waitress would not shut up & leave us alone. I didn't go there to have a conversation with her. Clearly we were having date night. Go. Away. Both times I was there it was like that. Maybe because it was late night & she was bored, but I did not appreciate it.
The other one on E Flamingo is the bomb diggity do da. It was the first one we discovered shortly after moving here & still my most favorite late night diner. The food is huge portions, good pricing, appropriately attentive staff.