First off, about Panda Express as a chain... I can't say enough about this place. If you're looking for high quality fast food, look no further (well, assuming you like Chinese, that is!).
Panda Express uses FRESH ingredients in all their food, which really sets them apart with so many other places. And it's not just a claim they make... you can see them there in their freezer. One day I actually witnessed them carrying in crates of fresh mushrooms! The recipes they use are simply wonderful - ESPECIALLY the orange chicken! If you haven't tasted this, then you are really missing out!
There prices are very reasonable... you can a great quality meal, fast, for about what you'd pay at the local drivethrough.
Now, about my local Panda Express. My experiences here have generally been excellent. The restaurant is always very clean and well kept up, the staff is friendly... my only complaint is that often, if you go in close to closing time (around 8:30 - they close at 9), the food is sometimes cold, has been sitting awhile, and there are very few things to choose from. While I can see why they don't want to make a whole batch of food close to closing, I find it rather disheartening as a customer to go in and then be expected to pick from a small selection of old food... If you go, I suggest going before 8 or so in the evening, to gurantee you get fresher food and have more choices.