I still use the N900 as my main phone and the hardware works fine. 3G and even 2.5G are both still supported where I live and there are no signs of it disappearing any time soon where I live, USB Type-B Micro cables are still widely available, Televisions still use infrared, etc. So for me the hardware is as usable as it ever was.

The hardware is outclassed in speed by modern devices but that does not make it any less usable than it was in the past. Personally I would be willing to pay a lot for an upgrade like the Neo900. The N900 still has nice features that modern phones typically do not have, like a keyboard, infrared, larger part free software, etc.

Personally I would pay big for a Neo900, even though the hardware is old. It is better than what I am using and loving right now. I find it really unfortunate that the project did not succeed.