I think it's obvious that most people wants a device that 'works, quickly and easily out of the box' except certain type of developers that are trying to conquer a brand new platform with clear incentives.

It's the degree of "mucking about the system to reach a certain idealized promise" that people have different tolerance for.

For example, one of the basic things that 'smartphones' are supposed to do is to sync your 'PIM' data from your main computer. These are:
contacts, calendar, notes, tasks list and bookmarks. For most existing smartphones (iphone, bb, winmo) they can do it 'quickly and easily' with Windows, OSX and Linux. Ironically, afaik, the N900 is only guaranteed to do this to a Windows PC for now.

Given what seems to be a big achilles heel, to a user who hasn't migrated their personal data to cloud computing (Say Google's), this should be seen as a considerable disadvantage to this system. You can buy the N900, you can sync it to most of your online data cachets (mailboxes, maybe bookmark, limited icals) but you'll have to break your normal workflow and opt to either unsync-ed data or to migrate your whole workflow to the n900 itself. Sure, it lives up to 'mobile computing' tagline, but i wouldn't want to be limited to it when i'm sitting on my desktop facing a full keyboard and a 24" screen.

I think the sync issue is a particularly big sticking point which doesn't have a simple and straightforward solution that can be provided by the community, unless Nokia ports Ovi Suite to OSX and Linux and fulfills the features parity against their competitors.