[salicideblock]

Portuguese (at least the one from Portugal) has 9 vowel phonemes, compared to 5 for spanish. If you count the nasals it's 14. And you can add some additional vowel richness in diphthongs.

It's very very varied phonetically when compared to the neighboring Spanish, which IIRC underwent considerable simplification at in the 16th century with unification of Spain.

I've heard many French and Spanish native speakers expressing the difficulty to understand it.

Source: Portuguese native speaker with decades-long immersion in Spanish and French-speaking communities.