My old rusty thorsmork couldn’t play flash HD video any longer. Although I do not plan to retire it yet, I needed a new computer.
My wife was not that happy to have another ugly PC in our apartment, and thus she offered me an iPad! Not really open source, but she chose well as there is no satisfying foss solution for a tablet PC yet, IMHO.
A tablet cannot replace a complete PC, but I use my PC much less now, it can be a week without using it. And it would be even less if I would have a real keyboard for the tablet!