Moonrat asked what the hardest language to learn REALLY is.
First, there are people in second language / foreign language studies who really try to document and quantify this stuff. I'm not going to read any of those things before responding. Instead, I'm just going to pull it out of my head, because that's the true spirit of a blog!
or at least I'm lazy.
The first answer and most true answer is that we don't know. There are 6-7000 languages in the world and only a handful are regularly taught in universities. It's mostly what, English, German, French, Spanish, Chinese, Japanese, Greek, Latin, Russian, that are almost always available in a university. Various language-focused schools will add more: UH teaches about 20 more Pacific and Asian languages. Indiana is amazing at Central Asian languages, adding another 20. U Wisconsin's got a bunch as well... But, still, even that adds up to... 100, 200 languages? That's only about 1/30th of all the languages that could be taught.
But that's a rather boring answer, no?, so let's look at least at the main 20 or so that people commonly study. There are harder and easier languages for an English speaker to pick up. The Romance languages are far easier than East Asian ones, for example. Typically it takes 4 years of Japanese or Chinese college instruction to get to the same communicative level as 2 years of French or Spanish. But why? And this is where things do get interesting.
Moonrat offers Japanese up as one of the most difficult languages, and she's right. One thing Japanese definitely has going for it in the nasty department is its writing system. Japanese borrowed the Chinese character some millennium and several centuries ago, but Japanese is entirely unrelated to Chinese ("genetically" farther apart than French and Russian or even French and Urdu) and so it only kinda works. So they invented a separate writing system later based upon the syllables of the language. In fact, that wasn't good enough still, so they invented a third syllabic writing system, and the key is they continue to use all of them all at once. This means you have to know all the characters that make Chinese so hard, plus the additional writing systems, too. That's just mean!
However some other parts of Japanese are quite easy. In fact, with only a couple exceptions, an English speaker can make almost any individual sound of the language with very little training and it's in the ballpark of accuracy. Compare that to, perhaps Xhosa of South Africa which contains a whole series of consonants called clicks that can be voiced, unvoiced, nasalized, not nasalized, all of which are entirely absent from English. The English speaker doesn't even know where to begin in saying them. But are such foreign consonants (from an English perspective) harder than the tones of a language like Chinese? In Mandarin, there are 4 pitch patterns (called tones) that are placed on almost every syllable. Saying the same syllable like ma with a different tone gives you a different word. This is extremely difficult for an English speaker to consistently produce and hear accurately.
However, while Chinese might be harder phonetically than Japanese, things reverse again with grammar. Chinese grammar isn't all that bad to an English speaker. A sentence still comes out in the order of subject, verb, object. Chinese doesn't really inflect words at all, and modern English does that only minimally as well. (Inflection: Latin is rather robust at it: amo 'I love', amas 'you love', amat 'he/she/it loves', amamus 'we love', amatis 'y'all love', amant ' they love' -- and that's only the present indicative. English still inflects some: I love, you love, he/she/it loves, we love, y'all love, they love, but look in that example there's only one change left in the 3rd person form. And Chinese doesn't really inflect at all: wo ai 'I love', ni ai 'you love', ta ai 'he/she/it loves, wo-men ai 'we love', ni-men ai 'y'all love', ta-men ai 'they love' -- The word 'ai' never changed at all. Now, that was easy.) However, Japanese does tack on tons of endings to nouns and verbs and can then shuffle word order around, making things harder for English speakers again. Moreover, they have some types of inflection that are hard to comprehend for us, namely a system of honorifics. Verbs change their form depending upon the level of formality and status (honorifics) that you are conveying. Oh, English speakers represent status of the listener, too, (we speak differently to Mother Theresa than to the moving van guy), but it's not part of the very grammar of the language.
So which is harder in the end? It's going to depend in part on who's learning. Are you naturally better at making sounds, at hearing, at grammar, at memorization of images, etc.? One person just may never get Chinese tone, but succeed at complicated Japanese grammatical structures. Another could be the opposite.
It's worth noting that most of this stuff I've talked about is not hard for children. There are probably some exceptions, but generally Xhosa children speak as easily as English children as easily as South Ossettian children. One definite exception to this is writing. Writing is an artefact in a way that speech and native signing (like ASL) is not. Memorizing characters simply takes years for a Chinese child, while Spanish has a writing system that quite closely matches how it sounds.
Did I answer you, moonie?