I trust Nokia to make a good quality handset actually.
If I will be getting the last maemo/meego device depends very much on all the standard considerations: price, hardware specs, availability date and software.
I always buy my phones based on the current software. And considering Nokia's recent Windows phone plans that seems to be the best advise to give to anybody. Don't be tempted to pay more for a device because of promised software updates.
Inform yourself about what a product currently can do, what known bugs you may have to deal with and the currently available third-party applications. Base your decision on that.
Phone manufacturers in general don't have a good reputation when it comes to updates for phones. Even Apple: they do provide updates, but often there are issues with older models. Updates for Nokia phones are always late, and SE and Samsung are very vague about release dates of updates.

If an updated N900 was available now (with galaxy S/iPhone 4 specs), I think they could sell it for something like 400 euros, and I would probably buy it.