I highly recommend Pike's milkshakes and other desserts. The old-timey atmosphere is fun, but the service also seems to move at an old-timey pace. It often feels as though it takes forever for your basic meal to arrive. The food is good (I like the grilled cheese), but not amazing enough to wait that long.
It's packed on the weekends. You'll find tons of families and little kids there.
In the summertime, it's fun to sit outside and watch the light rail go by and enjoy a milkshake.