BlackBerry is looking to launch its fightback this week with a new high-spec version of the trademark handset.

The smartphone has been in decline in recent years largely due to the growth in Apple iPhone and Samsung Galaxy S3. But experts say the BlackBerry 10 (BB10) should give them a run for their money.

One expert who has held and used the device ahead of the launch said it had “high specifications” that allowed users to do “good stuff in a couple of clicks”, which would appeal to both businesses and consumers.

But another questioned whether the launch, delayed from last year, meant the brand’s owner, Canadian firm Research In Motion (RIM), had left it too late.

Malik Kamal-Saadi, principal analyst with Informa, said the new operating system (OS) on the two expected handsets was a “trump card” that could see it win back customers lost through the poor performance of the previous BlackBerry 7 phones.

Kamal-Saadi said the system would be appealing to both business and social high-end users in Europe and North America, where BlackBerry lost the most ground over the past two or three years. But he added that the software was akin to the first generation of iPhones in being so radically different it may take people a little while to get used to it.

Investors will “leap into the sky” if BB10 sells more than four million units in the first three months on sale, he said, but sales of between one and two million would be okay. Anything less than one million would be a “big mess”.

He pointed out that the first iPhone, which went on to become a phenomenon, did not exceed four million sales in the first quarter year of sales and the less popular Windows phone sold between one-and-a-half and two million.

BlackBerry’s handsets revolutionised white-collar working a decade ago and are widely credited with kickstarting the smartphone boom.

BlackBerry is to launch two handsets, the Z10 and X10 today.