More than adequate for a night or two
This is a good deal for staying one or 2 nights in downtown Denver, if that is where you need or want to be. It is very conveniently located near the 16th st mall, and all points of interest downtown. Public transit nearby is absolutely amazing. Iti s a mere 7 blockss ' walk to the free downtown shuttle service, and the RTD, which will get you simply to and from the airport for $11 each way. 
Colfax IS a very noisy street, and the rooms open up to the outside rather than on inside hallways ( pretty typical of Econolodge) , but the location is otherwise great. I have stayed in this area several times and never felt it was dangerous, but i do not walk around much here at night. The street noise was my only concern. But even as a very light sleeper I was able to get a full night's sleep.
Reception clerk was wonderfully helpful, earnest, and kind.