Well, when you put it in 'what *I* thought' terms, how can there be a debate about it?
It does not allow you to, once again, replace components of the system or interface without ruining said system/interface... just like Maemo.
It does not actually do much of what I expect from Linux--flexibility of software--given the closed-down nature of the kernel (if you try to compile your own to support some features, you're left in a difficult situation for support of hardware components.. again).
Harmattan also lacks the ability to run on other hardware--something that at least MeeGo does (or is trying to) do.
The N9, as a handset, lacks a replaceable battery, it lacks any kind of expansion (SDHC or microSDHC), it's just--sadly--limited.
Sure it has a lovely looking body and an attractive AMOLED screen, but there's an array of similar or better (Samsung's SuperAMOLED+ for example... and even in higher resolutions) than the N9 already available.
It's just too little, too late and there isn't even that ONE great advantage that Nokia COULD have taken advantage of: Open-source and community. Sadly, even the Android crowd has managed to do more with far less openness.
You don't have to agree, just take a look around the XDA forums alone for some evidence of progress everywhere else.
I still hold out a glimmer of hope, yes, but I really don't think Nokia is interested in listening to us despite the successes of Google, Red Hat, Canonical and other far more open-source and community-friendly high-tech companies that have successfully competed against Microsoft and appears to be winning.