When I went to the 5 spot for the first time about 5 years ago, I was like "wow, this is THE Seattle restaurant for the general crowd." They do diner food, hence the mainstream feeling, but they do it well and they add themed twists. To my dismay, for several years, I found the themed entrées to be quite small, though flavorful. One time I got 3 tacos, and they were about 2.5 inches long - I don't care if there were 3, they were tiny!
Recently, I treated a big group of friends who helped me move to a 5 spot dinner, thinking "Oh, it will be just ok." That was not the case! I had the pork chop dinner, and it was great. Very clean flavors, mild herbs, and fresh veggies. I forget what the theme was, but my five fellow dining companions enjoyed their meals very much.
I have not had the opportunity to reevaluate their breakfast, however. I remember the long waits (where in Seattle do you not wait at 10am on a Sat/Sun?) and the burnt hashbrowns that sat on the griddle for a liiiitle bit too long. The bloody mary's made up for the mishaps, though it left with an "eh" feeling about their breakfasts, as they too declined in quality through the years.
TIP: Their late night happy hour (10pm and beyond, I think) has excellent prices. PBR for a buck, mac and cheese for five bucks, red beans and sausage for five bucks and a few other things. Its a great pit stop before going out, or if you want some late night grub.