While nothing is particularly wrong with Guido's, it is not a place I go unless I am with a group. I only ever go there during the day as the crowd at night is a bit too annoying. Tends to be frequented by young (early 20s) looking to score. Not really my scene.
For the food there are better burgers & sandwiches, better nachos, and better salads at the many other places downtown. The staff is very friendly and the prices very reasonable but again I can find that at most of the places downtown.
During the summer it is nice to sit outside as they have a prime people watching location.
Guido's is good for large groups.