I've had Dave's subs twice and they are pretty good. I had two of the veggie subs with whole wheat rolls. They have enough cheese for protein but otherwise have lots of veggies. One of the sandwiches was hot and the other cold, a choice you make when you order. Hot's a lot better.
Dave's is going against the trend of letting people pick all their ingredients. At Dave's you can't substitute items although you can add them. It's good for people like me who don't want to think through all of the ingredients, but if there is something on the sandwich you don't like you'll have to take it out yourself or just eat through it.
Aside from the subs, the angle is the 60's rock music, with lots of memorabilia on the wall. Fun to look over and reminisce (or imagine).