Playbook multitasking missing alot of things. Like background services, push notification, system-wise location-based reminder/schedule alert.
In default mode, everything are pause in background, nothing work, even browser stop loading. In showcase mode, you must keep app alive to able receive notification (todo, task, alarm,... app). Not to mention you need to micromanagement app because when system out of memory, apps just refuse to open or crash.
While it is cool to have a game still run in background, it isn't a elegant solution to do multitasking on a single-window/single-app tablet device. What is the point of app still render UI in background when you can't see it anyway.
That article is hilarious when they don't even compare the app quality and selection which is a huge factor in any general purpose computing device.
You hardly can find a half-decent PDF viewer on the Playbook, let alone a PDF viewer/manager/annotate in a same class with GoodReader. And this is just one of many basic function.
BTW you guys must visit their forum, it's filled with people who think QNX is the future of mobile computing and every other tech company are so scared of it they must team up and bash RIM via media =)