Coverage in the Chinese media means the expo is bound to offer at the very least an excellent marketing opportunity.
And some foreign firms may make worthwhile connections: the organisers estimate that more than 150,000 buyers, primarily Chinese, will attend.
It would not take many Chinese deals to lift the fortunes of, say, a Sri Lankan cinnamon producer.
But privately, some bigger companies are grumbling.
China's economy long ago grew big enough that trade fairs need to target specific industries if they are not to be unwieldy,
but the expo covers everything from biomedical research to furniture.
Even the focus on imports is not as distinctive as billed: most Chinese trade fairs promote imports alongside exports these days.
The biggest annual event, commonly known as the Canton Fair, was renamed in 2007 as the China Import and Export Fair.
Firms also gripe about feeling political pressure to attend. It might not benefit you much, says one participant, but staying away would bring unwelcome attention.
There will inevitably be a flood of praise for the expo from companies eager to please China. It should be treated with caution.
Firms have been asked to announce big deals during its six days.
A European diplomat says the commerce ministry approached him six months ago
to encourage firms from his country to re-announce recent sales agreements or bring forward future ones.
The goal is to be able to trumpet a huge boost to imports at its conclusion.
Critics would forgive such publicity stunts if China also took the opportunity to tackle deeper grievances.
Government advisers have said that something big will come out of Mr Xi's speech on November 5th.
Steeper tariff cuts are one possibility; tariffs on imported cars, for example, were trimmed this year to 15% but are still high by global standards.
Or new protections might be announced for foreign intellectual property.
Carlo D'Andrea, of the European Union Chamber of Commerce in China, says that for the expo to count as a success, it must be more than a show.
Yet the expo's highest virtue is its symbolic value. The growth of Chinese imports is a long-term trend.
In 2000 China was the world's eighth-biggest importer, accounting for about 3% of global imports.
Last year it was the second-biggest, behind only America, and its share had risen beyond 10%.
For much of the past three decades the promotion of exports was central to China's economic strategy.
In promoting the expo, Mr Xi is showing that the government not only welcomes China's transformation into an import superpower, but wants to speed it up.