BlackBerry officially unveiled a new phone this week with a very unusual screen shape — it's perfectly square.

The BlackBerry Passport features a "unique 4.5-inch square screen with full HD capabilities," said a post on the company's official Inside BlackBerry blog earlier this week, which included photos of the device.

It has a separate keyboard below the screen, like traditional BlackBerry smartphones, but it contains only letters, not numbers or punctuation.

The square screen gives it similar viewing space to a phone with a rectangular screen that measures five inches across the diagonal, and allows it to show 60 characters on each line, instead of the 40 on most rectangular smartphone screens, wrote Matt Young, author of the blog post.

"Academic research has shown that the optimal number of characters on a line in a book is 66 characters," he said.

He  added that users will also no longer have to worry about whether the phone is in portrait or landscape orientation for optimal viewing of documents, spreadsheets or images, making it ideal for professional users such as architects or doctors.

The Passport was first announced by CEO John Chen during an earnings report in June, when he said there would be an official launch in London in September, the technology blog MobileSyrup reported at the time. Since then, various photos of the device have been floating around the internet.

At least some tech watchers seemed open to the idea.

"The Passport could help BlackBerry reconnect with its traditional business and government customer," wrote Ben Fox Rubin of the technology news site CNET, "though some may still be wondering whether a square phone will fit in their pockets."

Those commenting on the official blog post had mixed responses.

"In my mind this could quite possibly the best phone design ever," gushed a user named Roy Whitney.

Another user called OWC wrote, "No thanks. I miss the alt and shift key!"