Many issues are being talked about here but the fundamental issue is obviously if the N900 is a suitable device for you.
The n900 is a developers handset that was released for the benefit of potential developers to get fully involved developing apps for this Linux based device and that has been exactly what has been happening on the device since its release last year so if you need a device to start developing apps etc for then the n900 is for you.
Nokia are not able to confirm the future of the N900 simply because they are awaiting as much development as possible and my guess is that this will lead to a base platform for the next Linux "flagship" Nokia will release.
The N900 has very basic phone functions with a lot of apps and functions missing from what we have became used to on a Nokia device.
On a positive note the N900 is in fact fully programmable and can be a suitable device for a fully developed platorm in the future, whatever it will end up as will depend on the development success in the future.
Meego is indeed the direction Nokia are going and no one knows when this will be available in a complete workable state as a base platform for any device let alone the n900.
For now my thoughts are NOT to buy the N900 if you want a fully functioning device with no conflicting problems within the OS, as said erlier the N900 is a developers tool and obviously has a long way to go if it ever will reach a final point of software completion as this device is primerally designed for developers to develop linux based software for mobile devices of the future.
The biggest flaw the n900 has is the USB port that will detatch itself from the motherboard due to bad design, this has now i believe finally been accepted by Nokia as an official design flaw and this means it is obvious Nokia will go to a better design as soon as the development is at a stage when a complete OS can be installed with the apps fully working without conflicts etc and please note that the os conflicts are simply due to installing new developed apps etc that are causing the partly developed os to crash or malfuntion.
Please also note that a complete fix is indeed possible for the usb flaw but unless Nokia officially implement this on all repairs being sent in (i doubt this will be the case) then to self fix will invalidate warranty so best to wait till the warranty period is over before implementing the usb port fix.
The N900 is a developers "toy" and will i guess at some point reach a state of full usability once development has moved on to the stage of putting together a fully non conflicting os of maybe Meego.
So the choice is yours but a clear point is the n900 is NOT a device that is fully functional with the apps we are all used too and requires time to get to that stage.