There is seating outside, but the inside is simply a very small area in front of the counter.
I was there in June '06 and there were always a few people in line ahead of me, but it was never inordinately crowded, including in the morning. Note however, that I always went there early in the morning, about 7 am.
A snack credit is worthwhile for a breakfast pastry, although it may be a better idea to pay cash if it isn't a very expensive snack. For example, a donut is only about a dollar, so I would pay cash for that.
It is worth a CS credit to have a sandwich and a desert there. Although there are only four or five sandwich choices, they were all quite good. You might check one of the menu websites to see what is currently available. If you haven't already, try http://www.wdwinfo.com/wdwinfo/dining/disneydining.cfm.
I can confirm that the sandwiches are large and very good. My DW and I ususally share one at lunch. It is very pleasant to eat at the BW tables outside when the weather is good and the gulls are not too aggressive.
Absolutely worth a CS credit - ITA with PP's - sandwiches are great. We used most of our snack credits there too as we were staying at BWI and did pastries in the AM and desserts as a midnight snack!