All other phonemes in Japanese exist in English phonology. Which means that, with a bit of practice, it isn't difficult to speak like a native. Most of it is delivery, and the Japanese do have specific habits when it comes to that.
I don't think that's entirely true. There is a whole world of bad pronunciation out there, even from foreigners who learned the language and live in Japan. Plus, even if people are aware of the Japanese syllables, different nationalities add all sorts of inflections and word stress that make it almost painful to listen to.
Also, the "fu" (ふ) sound is a bit problematic for English speakers at least. While I would pronounce it with a hard "f" the way most English speakers would, it's actually a cross between fu/hu/wu (i guess the closest would be a soft "who") - the "f" part is very soft and as a non-Japanese speaker I am very aware that I don't quite pronounce correctly, but do my best. Even for my students, any word or name that is spelt with "fu" (like Fukuoka, or Fuka) will often be mis-spelled as Hukuoka or Huka.
