Panera is a chain of bakery restaurants; it is a competitor to Le Boulanger and similar bakery restaurants offering onsite baked goods (breads, pastries, bagels, etc.)
We've had breakfast 2x and also purchased bread (sliced thin or thick - your choice, or not sliced at all!) on both visits.
We really enjoy their breakfast sandwich options, esp. as you can ask for egg whites only on any of them.
The coffee is good - perhaps a tad weaker than that at Starbucks and Bagel Street which are in the same strip shopping center. Order coffee onsite in a mug and you get endless refills.
Staff are really pleasant, helpful and efficient. Prices are standard for the area (Mountain View/Los Altos border). The menu is easy to read on the big boards, or you can pick up a paper copy to read at the table.
You order at the counter, pick up an electric "puck", and you food is brought to you when ready.
Coffee and tea are self-serve.
This Panera is quite large, with one dining area adjacent to the counter, a very large (public) room in the back, and a huge patio with lots of umbrella covered seating. The patio is nice on the weekends; on weekdays it's a bit close to busy El Camino for my ears!
We've yet to try the lunch sandwich/salad/soup menu, but expect the quality to be quite at the top of the list for this type of establishment.
Rating would be a 5, except for the weekday noise on the patio.