After working for quite a long time in small buildings/companies, it is quite a change moving all of a sudden to a large business, even if it is just for an assignment. So, what are the main differences? Contrary to popular belief, large companies are not always completely strict and bureaucratic in every sense. But then again, it depends what you are asking for/aiming at. Large companies have better organisation, and the effect of a crisis seem to take longer to create a real impact on the workers.
In larger companies you may have access to a few privileges small companies can not always aford, like proper lighting, sanitary conditions, unlimited coffee :P, and other details. Workspace, on the other hand, seems to be more of an issue in large companies, which might not be able to afford wasting space for the sake of commodity.
In conclusion, the main advantages in being in a smaller business are space, smaller hierarchy, more direct contact, stronger bonds between employees, etc. The advantages of being in a larger business are usually related with larger benefits, more recreational activities, larger amount of coffee and goodies, better toilets and facilities (specially when the company is aiming at an international standards certification), etc.
These are only my initial points of view, of course.