+1. I sometimes hear nostalgia for the N900 but personally I don't get it.

Anybody could run a full multi-tasking OS on a mobile device trivially. The performance sucked and you killed your battery super quickly.

The innovation was in multitasking that didn't result in a terrible user experience, and it took a lot to get there! And the answer wasn't "welp what if we just treated this thing like a desktop".

And it's still not a fully solved problem - there continues to be a lot of movement around how apps are defined so that they can be efficiently concurrent! (or at least give the appearance of concurrency)