Reporters at the American technology network The Verge, and digital media website Mashable, were among those to get their hands on Royole’s FlexPai device at the event in San Francisco.

Both reporters confirmed that the folding technology worked – halving the size of the 7.8-inch (20-centimetre) plastic screen with one 180-degree twist.

“Yes, it feels a bit gimmicky, but the FlexPai does actually deliver on its promise of being the ‘first foldable smartphone’,” Mashable’s reporter Karissa Bell said.

However, the FlexPai is far from perfect.

The device does not fold flat and was quite difficult to hold, Bell said, adding that the plastic display lifted a little over the hinges and made a “crunching sound” while folding.

She said Royole told her the issues were “due to the adhesive used in the engineering samples.”

The Verge’s reporter Nick Statt said that when folded, the phone was “bulky” and “feels miles away in quality” from a high-end smartphone.

The software, a bespoke version of Android 9.0, seemed “extremely sluggish” and buggy, he added.

“This device is very much a first-generation product,” he said. 

Watch Royole’s demonstration video for the FlexPai:

Royole said the foldable phone would go on sale as a consumer device in China in December, but in the US it would be available only as a developer model, costing US$1,318 for 128 GB of storage and US$1,469 for 256 GB, according to Mashable.

Two days later also in San Francisco, Samsung obscured the final look of its device by placing it in a case.

They described the Infinity Flex Display as "the foundation of the smartphone of tomorrow" and said they intend to start production within months.

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This article originally appeared on Business Insider.