I "visited" this diner with my parents and newborn baby on a trip to Niagara Falls. This diner is in the same building as the Niagara Falls Hotel and is next to the lobby. We arrived there at around 2:30 pm in the afternoon, and the last customers just left so the entire diner was empty. There were at least 4 waitstaffs there. We were waiting in front of them while they were "busy" with doing nothing in particular. They all saw us standing there waiting to be seated (how can they not? we were standing only about 3 feet in front of them!).... and we waited for at least 20 minutes without being greeted or acknowledged. Bear in mind, there were no other customers seating in the restaurant. We left feeling really lousy on what supposed to be a fun trip. I promptly wrote a letter to Denny's headquarters but got just a customary "we'll look into this matter" reply.
Check out the Niagara Falls restaurant guide as well. Boy, we are glad that we did NOT end up having our meals there. You'll pay a handsomely for peanuts! After 2 years since our visit, it looks like they got worse. We didn't think that could be possible!