Went to Valencia - Depor on Sunday night. Thoroughly enjoyed both the match and the whole experience.
The general atmosphere at La Liga games is considerably more laid back from what I've seen (3 games now) than football in England. More subdued in terms of support and more of a social occasion. The Valencia 'ultras' were brill mind, plenty noise and banners etc. Seemed to be lots of protesting about the 11pm kick off time and a fair few anti-Madrid/Barca chants.
Valencia were excellent first half but barely turned up in the second and allowed an average Depor side to dominate. Great standard of football (ignoring some shoddy defending and lacklustre off the ball stuff) though and probably a fair result.