What can you say about Denny's - the food is what it is, its breakfast food. As long its not completely messed up, you cant really have any complaints. Service is what determines the customer satisfaction at places like Denny's.
We had pretty good experiences with Denny's, in general, at various locations. So we were excited to see a location open up in Champaign. We have been there many times by now. The service was acceptable. Depends heavily on who is attending to you and what mood they are in. But overall, we didnt have many complaints.
There was one instance when we ordered the milkshake, she gave us just the serving glass and did not give the mixing glass with the "extra" which they claim to be part of the order. The overall experience on that day was below par.
The wait staff definitely needs more training in doing their work and keeping customers happy. They come in knowing what the food is going to be like, make them come back and keep the place running with a good customer service. Not sure why it is so hard to understand this simple logic.