I definitely like Jimmy John's. It's my favorite place to pick up a snack in between classes.
I like simple sandwiches and Jimmy John does some great, cheap, simple sandwiches. Their 'slims' (no veggies or sauce) on the menu are only $3.25, plus I can pick up a ~14" piece of day old bread for like $0.50, and I've got myself a full meal for like $4; I can't complain about that!
The staff have always been really friendly. I think they're forced to sort of yell "Hello" and "Catch you later" as you enter and leave the shop. But they sound sincere enough, so I'll say that's a good thing for them to do.
But, no complaints here. However I can't really complain about nothing and give it 4 stars, so:
Analyzing their pricing a little more carefully I discovered that for $0.75 more you can go over to subway when they're doing the $5 footlongs and get like 3-4 more inches of sandwich for 75 cents more. I did some calculating: You'd save 12 cents an inch of sandwich by doing this! Over your college career that'd be approximately $240 (assuming an average consumption of 2 sandwiches/week for 4 school years). Just some food for thought.
Luckily Jimmy John's gives me a $1 off for not getting veggies (which brings me to about 1 cent/inch cheaper than subway), so I don't have to make that decision.