It is good, but it depends on the country of origin and their laws. Both multiculturalism and assimilation stems from the country of origin. If the country of origin won't allow for such, than multiculturalism and assimilation won't happen.
Take Lima, Peru for example. It has quite a Mestizo population... compare it to say San Francisco and New York... and you'll see a startling contrast. The immigrants actually become part of Lima, Peru... and with open arms because the laws and practices cater to such. Take the Chinatown in Lima, Peru as another example, it is relatively small compared to the Chinese that live outside of it.