[quote name='Panda']^_^
If you think Japanese is hard, take Chinese. *dies*[/quote]
Having learned both languages, I'd have to say that Japanese is a lot harder to learn than Chinese.
Chinese has the intonations that are hard to pick up at first, but you get used to them. And the writing system's pretty tough but Japanese has the same thing in Kanji, except Kanji characters can sound completely different depending on the context or the word. Also, compared to Japanese, Chinese has almost no grammatical structure.
On top of that, throw in 2 more alphabets, politeness levels, layers and layers of grammatical structure, differences in female and male speech, a million non-Japanese words they adopted and twisted the pronunciations of, and strict social guidelines and formalities of speech, and it's not even a close race. No, I'm not a Japanophile or Japanese/Chinese, so I have no bias.
I think Chinese might come off as being harder than Japanese to first time students because the concept of the different intonations is so foreign to them and they're thrown immediately into the Chinese logographic writing system. While in Japanese, you're eased into Hiragana and Katakana first and then slowly introduced to a few Kanji characters at a time. But keeping track of all the characters and rules get pretty tough in the higher level courses.