Some data to consider:
Advantages: Essential if its niche of business concentrates in Spain.
Disadvantages: Less coherent for projects than they are not Spanish or speakers of Spanish.
Something of history:
The domain was created in 1988. Nowadays it is used for webpages in this language that not necessarily correspond to Spain. After surpassing innumerable conflicts, relaxation, streamlining at the time of the registry and a substantial reduction of the price, at present they do not exist requisite specific to register it.