Provia is a medium ground E6 film IMHO, which means it's mighty usable film overall, it covers some 80% of my E6 needs. I shoot E6 to get those special colours. Velvia sometimes is overkill or too narrow-purosed and E100Gs were too subdued to "punch you into the face" after scanning for the lack of better wording - unless I want a very low grain and very limited DR I'd rather shoot Portra.
Punta del Diablo sunset by tsiklonaut, on Flickr
Puente de la Mujer by tsiklonaut, on Flickr
La Boca colours by tsiklonaut, on Flickr
Provia 400X is entire different matter though - I think it's the best film for recording blues, beats even Velvia 50 (that makes blues with purple cast):
European Southern Observatory (ESO) by tsiklonaut, on Flickr
Valparaíso by tsiklonaut, on Flickr