[omaranto]

    I think this is even more true for Chinese than most other languages.

Commonsense indicates the difficulty of learning a language doesn't depend solely on the language in question, but on how similar it is to languages you already know. An extreme example is that if you already speak Mandarin, learning Mandarin is a no-op. As a less extreme example, I'm sure that learning Mandarin is easier for a Cantonese speaker than for someone who only knows English and French.

[lmm]

Commonsense does suggest that, but I've heard such a wide variety of people with different linguistic backgrounds say that Mandarin was the hardest language they learnt that I'm inclined to believe there is some real underlying difference.

[Zarel]

Well, considering that Chinese is mostly a linguistic isolate, that doesn't necessarily contradict the thesis. Japanese has a writing system and a lot of vocabulary borrowed from Chinese, and I know less about Korean but I think it also has plenty of vocabulary borrowed from Chinese. Do any of your friends natively speak one of those languages and still consider Mandarin more difficult than, say, English?

[jon2512chua]

I'm a Chinese, and I can easily understand written kanji (one of the 3 Japanese writing systems) as it's essentially traditional Chinese characters, but the pronunciation is a whole different game altogether. From this I'm assuming that it's the same for Japanese speakers to recognise some Chinese characters, thus making it easier for them to learn.

[rangibaby]

In Japan, you learn both Japanese and Chinese readings for kanji. Except the Chinese readings in China are different to the ones in Japan. A lot of people thought I was strange when I was pointing things out on a menu, but couldn't say what they were. lol

[jon2512chua]

Wait so the Chinese reading in Japan is different from the Chinese reading in China and most parts of the Chinese speaking world (ignoring the influences of accents)?

Can you provide an example please?

[Zarel]

Here's some that are different:

    方法 (method)
    In Chinese:  fāngfǎ "FONG-fah"
    In Japanese: houhou "HOE-hoe"

    日常 (everyday, ordinary)
    In Chinese:  rìcháng "ZI-tchong"
    In Japanese: nichijou "NEE-chee-joe"

    七月 (July)
    In Chinese:  qīyuè "CHEE-yue"
    In Japanese: shichigatsu "SHEE-chee-gah-tsoo"

(Yes, 'shichigatsu' is seriously the Chinese reading of July; the Japanese reading would be 'nanatsuki'.)

And some that are similar:

    開始 (start)
    In Chinese:  kāishǐ "KAI-tsi"
    In Japanese: kaishi "kai-shee"

    第三 (third)
    In Chinese:  dìsān "dee-SAN"
    In Japanese: daisan "dai-san"

(Note that the pronunciation guide is somewhat approximate since certain sounds don't map well and English vowel pronunciation is a mess.)

I've heard that the Japanese on'yomi (Chinese) readings are generally closer to Old Chinese than modern Chinese is. Also, notice that Chinese is tonal and Japanese isn't.

[lmm]

Natively no, but one of them had learned Japanese before and found Chinese much harder even having that prior vocabulary.