Pros
If you ever wondered how major companies run their websites you can come here to find out. Very brisk culture of getting things done and working through problems. Engagements are usually between 1-6 months so there's no risk of getting bored. Plenty of opportunities to advance, learn from the best, and get your hands dirty.
Cons
The company has grown very fast so there are growing pains, especially in how they've expanded horizontally rather than vertically. There appears to be a bit of attrition at the project management level as people try to figure out what to do next.