Research In Motion co-chief executive Mike Lazaridis took to the stage at the All Things Digital conference this week, where he played down fears about the shrinking economy and competition from the iPhone.

Lazaridis was interviewed by The Wall Street Journal's Walt Mossberg, and responded to questions about his own products and those of RIM's rivals, including Apple. He trumpeted the scalability, security and manageability of BlackBerry smartphones, and stressed the difference between iPhone users and serious smartphone users.

"If the whole reason you are buying one of these is to watch streaming video outside your office, that's a very different value proposition than being connected to your world, your friends and your business in a secure and reliable way," he said.

"This computing platform is a personal one, and has to represent our values and our style. [The smartphone] is something that we are depending on and expecting to be perfect, and RIM will always make sure that the voice, the messaging and the ability to integrate with your documents is solid."

However, the average smartphone user now wants access to more features and functionality, as demonstrated by the huge success of Apple's iPhone App Store.

Mossberg argued that the security of the BlackBerry platform could stymie developers by effectively working as a barrier to new and varied applications.

Lazaridis countered: "We've had application download on BlackBerry for years, [and] we have a strong reputation in the enterprise that we take very seriously. Now you have to develop for both the consumer and the business market. It forces a discipline, but it is not a barrier."

Laziridis was also bullish about the downturn in the economy, and RIM's ability to survive such challenges.

"I started RIM in a recession, and we have been round for 25 years. No matter what the short term situation, it always gets better," he said. "There is something about high tech that drives value, adoption and change. As long as we invest properly, we will be doing the right things when the economy improves."