While it's true Esperanto is not a national language, it follows the patterns common to European languages too closely to really be a neutral language. It's probably nearly as difficult for speakers of Asian languages as any other European language.
I meant politically neutral. I apologize for the lack of precision. I agree that Esperanto - although artificially constructed - is a European language as its main vocabulary and grammatical features are borrowed from romance, germanic, and to a lesser extent from Slavic languages. This is one of the few points I do not like with Esperanto.
On the other hand it is difficult, indeed, to create a really neutral language. Other artificial languages, like Lojban for example, are not based on natural languages as for vocabulary and grammar, but still use the latin alphabet. A completely unbiased approach would require a totally new system of symbols or letters, but then you run into problems with acceptance and the difficulty to learn such novel structures. As a consequence most artificial languages make a compromise between borrowing features from existing languages and inventing novel features.