I've been to Chompie's between 5 and 10 times and I always have a great experience.
When you walk in, the hostess will be to your left and the deli on your right. Great prices on yesterday's bread, by the way, and they still look really fresh (but I personally haven't tried them).
Like others have said, there is usually a bit of a wait to get in (especially on weekend mornings) but it's worth the wait. Prices aren't too bad--they're fair but if you're eating in and you tack on some O.J. and coffee, you'll be looking at close to 20 bucks for your meal alone.
Most of the time when I come here, I'm just grabbing something from the deli and taking it with me somewhere (like Tempe Town Lake or South Mountain). Solid experience every time I do this--just be sure to tell the person behind the counter exactly what you want exactly how you want it.