Smartphone users in Australia will have to wait for Bixby, the feature of the new Samsung Galaxy S8 that could decide the handset and its maker's fate.

The AI assistant will be rolled out to US customers on the phone's release on April 21, however international users, including Australians, have been left assistant-less and without a release date for the service on the horizon.

Bixby, along with Dex, is an essential key to the success of the phone release, which happened to much fanfare at a launch event titled Samsung Unpacked in New York on Wednesday.

The phone sports a dedicated Bixby button to activate the assistant, hinting at Samsung's confidence in the feature.

The company could readily expand its application if it was made available to third party developers and will be able to upgrade it easily via software updates.

Samsung broke with protocol to release details about Bixby via a blog post on the company's website a week before the release of the handset.

Reviewers have so far been tentative to state the fate of the Galaxy S8 and whether it can return Samsung to the front of the market again.

Many are awaiting to try the key features for themselves outside the perfect testing conditions on offer at the launch event.

Consumers have also tended towards the middle ground before getting their hands on the device.