I was travelling through Vietnam and thought it funny just how many diacritic marks Vietnamese text makes, and thought that English was better because it doesn't need them. Then I realised that - holy shit! - English needs them big time. Look at wind (air movement) and wind (wrap around), or wound (injury) and wound (past tense wrap). Or even read (view text present tense) and read (view text past tense).

Admittedly I'm only a monoglot, but Engish seems pretty brutal in expecting you to figure out the correct sounds from the context. A few diacritics sprinkled in could likely really help newcomers with appropriate sounds.

On a tangent, one of the things I like about written Spanish is that you know at the beginning of a sentence whether it's a question or an exclamation. It's always a bit weird when reading a long sentence in a novel, to get to the end of it and think "oh, that was actually a question..."