What is ironic is that you, english speaking guys, have difficulties with Spanish vowels... we only have 5 vowels, and you have almost 20 O_o... and from what i learned about English phonetics, you have all the vowels we have. English phonetics for a Spanish speaker is hell... because there are so many sounds we have never ever heard. The only sounds we have and you don't are: -j-, -r- and -rr-.
Yeah, English vowels get crazy. Which is why English speakers have problems with Spanish vowels, because we complicate them!
![Razz :P](./images/smilies/icon_razz.gif)
Take taco [tako] -- by the time an English speaker gets done with it, 1) any number of things could have happened to the first vowel depending on where you're from, and 2) the second vowel gets diphthongized -- not to mention aspiration -- so that where I'm from, people end up pronouncing it [tʰɑkoʊ] (myself included, I'm sure).
![Stoned Kermit :stoned:](./images/smilies/stonedkermit.gif)