Werd. There is no universally accepted phonetic system in English like there is in Japanese (even if there is, or if one was introduced, it's not currently taught, so it'd take years to integrate one). We have the alphabet, but unlike Japanese, each letter is not restricted to a particular sound.
On the other hand, we don't have to make up retardedly large (multiple) alphabets in order encompass every possible sound. English is much more simple in a lot of other ways. So is Russian (probably... I wouldn't know about learning it, I was just born there). This probably makes English much less daunting to learn (not to mention no Kanji).
I'm kind of starting to wonder if the reason why Asians may be more hardworking or even smart (arguable) is because they've made everything about their culture a pain in the ass (compared to America anyway). Chopsticks or spoon and fork... which requires more concentration? Chopsticks, obviously. What about society? In America, loose, vague, and pretty simple (if it's your boss or someone you respect, maybe speak with a tad more care). Japan? Crazy amounts of depth... who the fuck knows who's gonna be offended, etc?!
What about linguistics?
US: Basic words -> basic sentence structure -> more complex words & sentence structure. Somewhere in there is also the introduction of slang terms to simplify. The past/present tense stuff (and "they're/their/there, its/it's) may be a problem to some, but it's not hard to be understood.
Japan: To be honest, I don't quite know enough about the sentence structure. From my friend ranting about it on the phone while learning it, it appears to not clearly state the noun sometimes, and it can be very difficult to even put what is being said into text because of all of these rules about what you're writing down as opposed to what you actually hear (I hear him complaining about "what is this 'understood' bullshit?!" a lot)... but putting that aside they already get a massive amount of memorization training because of that huge (multiple) alphabet size and... then there's Kanji. It's just more of a challenge on so many levels.
... Just a mini-rant in a somewhat unrelated topic, totally uncalled for.
Japanese is actually really simple, it's just different. It's actually completely phonetic - so one set of sounds (46, I think?), which are always pronounced the same way, and always written the same way - If you see a word written in the basic Japanese alphabet, you can immediately see how to pronounce it, unlike English.
The grammar is very logical, with relatively straightforward rules, and few exceptions. Japanese only has four irregular verbs, for example, whereas English has more irregular verbs than regular. The only complicated bit is the kanji (and admittedly they are very complicated), but they're more like another layer on top of the actual language, so don't really have any effect on grammar etc as such.
The bit about not clearly stating the noun etc is also really simple: if it's already understood what you're talking about, you don't need to say it. So if you're talking about something, and the person you're talking to knows what you're talking about, you don't need to include it in every sentence, unlike English.
The only complicated thing about Japanese is the kanji. If it wasn't for those, Japanese would be one of the easiest languages in the world to learn imo.
Anyway, on topic: I listened to that Hatsune Miku video in the OP, and frankly was not impressed. You can immediately hear it's a synthesiser, it even has occasional noticeable glitches when changing pitch etc. There's no way that will be replacing real vocalists any time soon. Honestly, it's a bit disappointing; Japanese should be really easy to synthesise (since it has such a small set of potential sounds), so I expected better, really. Maybe some of the other vocaloids are better, but I can't see what all the fuss is about.
That Kashiwa Daisuke track rosstheferret linked, on the other hand, is really amazing. It's been a long time since I've heard an instrumental track that good.