Heins said in a statement Wednesday that "yesterday was the best day ever for the first day of a launch of a new BlackBerry smartphone" in Canada. In fact, he said, it was 50 percent "better than any other launch day in our history" in that country. Even better, he described the sales in the U.K. as "close to three times our best performance ever for the first week of sales for a BlackBerry smartphone."

The company has not released specific sales numbers, but, according to retail channel checks conducted by investment firm Jefferies & Co., preorders in Canada and the United Arab Emirates were "solid." The phone went on sale in Canada on Tuesday, and it goes on sale in the UAE on Feb. 10 and in the U.S. in mid-March. BlackBerry has said the delay in launching the device in the important U.S. market is due to testing by carriers.

Sold Out or 'Underwhelming'?

Jeffries also reported lines outside of U.K. stores selling the Z10, and said some retailers sold out of supplies, including the large Carphone Warehouse chain. The white model was reportedly selling faster than the black one.

However, other analysts have dampened the enthusiasm of some of the early reports. Investment bank Canaccord Genuity, for instance, has noted that most stores actually received fewer than 15 units, which were sold out over a two- to three-day period. It said reports of sellouts were due more to limited early supply than because of demand.

Additionally, a report in The New York Times said the line at a Bell Canada store in an upscale Ottawa shopping mall had only five customers when the Z10 went on sale. The Times described the reception in Ottawa as "underwhelming," and said the same scene "was repeated not just later at competing outlets in the mall but throughout BlackBerry's homeland."

Q10 by May or June

Canaccord Genuity said the Z10 has "closed the gap" between BlackBerry and its iPhone or Android rivals, but there were "limited differentiating features" and the training needed for demonstrations by store personnel led to a lack of enthusiasm by some store managers in Canada. The firm has, however, described U.K. sales as being solid.

In any case, some BlackBerry watchers have cautioned that strong early sales do not necessarily mean a continuing stream of buyers, and that the U.K. and Canada are among BlackBerry's strongest markets.

The Z10 and Q10 models, and the new BlackBerry 10 platform, were formally unveiled last week. At the launch, the company said the Q10, which has a physical QWERTY keyboard, would be available by April, but Heins indicated this week that the Q10 would not be available in the U.S. until mid-May or early June.

Since BB10's launch last week, there have been generally positive reviews of the new models and platform. The New York Times' David Pogue, for instance, described the Z10 as "lovely, fast and efficient, bristling with fresh, useful ideas." The Wall Street Journal's Walt Mossberg praised the company's "radical reinvention," and said it gave them a chance of getting "back into the game."