NITDroid still can't make phone calls. That's a prob for a phone, innit?

Nokia N9 and Nokia N900 are both phones. Never forget that. Unable to make calls is unacceptable unless you have that money and pocket space to waste.

Regardless... ICS does background tasks. You can download via the Browser, move files via Root Explorer and be responding to an e-mail quite easily. It doesn't tile like Harmattan does, but it's less serial tasking than iOS and closer to true multi-tasking than Gingerbread in terms of presentation.