Levente.Maier wrote:Which is the hardest then?
If "hardest" means "with the hardest grammar rules" I'd go for Italian or Romanian.
If it means "with the hardest pronunciation rules" I'd go for French or Portuguese.
My knowledge is limited (at various degrees) to Portuguese, Castilian, Catalan, French, Italian and Romanian. No idea what to say about the other ones.
"Central changes" are very common in many of Italian dialects, and in Italian to a lesser extent.