Bob's is great! I visited twice this past weekend to get the full effect. It truly is a dive bar, with only a few beers on tap and a small location. But the culture is great, the regulars are friendly, and the electronic darts game makes any night a great night. Beer prices are cheap, I think we paid $2.25 a bottle and $3.00 for all mixed drinks.
All-in-all, next time I am in Sioux City I will make a point to hit up Bob's at 7th and Omaha.