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For starters, it has a terrible selection of apps, Lam says.
"It's not their fault, and maybe it's even pretty good for a new OS with over 70,000 apps available at launch, but that doesn't matter for you because in the end, that means they're still far worse than the Android and iPhone/iPad libraries today," Lam writes.
For example, the OS doesn't offer Instagram, Netflix, Spotify, and Yelp. But even with the apps it does offer, some of them are lacking in quality, Lam says.
The operating system does shine when it comes to gesture controls, but it's lacking in the mapping area.
In short, Lam says he wouldn't tell anyone he cares about to even consider buying BlackBerry's new phones.
"You should not buy (the Z10) unless you have emotional and cultural reasons to love Blackberry, or some arcane enterprise reason I will not pretend to understand," Lam writes.