It is so and so. I tested phone calls and sms, and they seemed to work, while lacking polish on UI side. I don't know any email clients, and didn't notice that there would be one pre-installed. Package manager (gui one) froze, so zypper should be used.

Tested with N900. Class10 memory card (random r/w might be better with quality Class6 one). It was very sluggish in many occasions.
I'm curious on how well this could run with a device with more memory. I do not dare to try putting Mer/Nemo on my N9 yet, since I probably couldn't fix it if I blew it.

Overall it looks nice already, although I actually liked naivistic "meego" graphics better than the new shinier icons. It is still ok with current style though. Graphics were very smooth when not chugging with lack of memory or because of bugs.

I wish 3g data would work, but alas it doesn't even while there are settings preconfigured for Finnish telcos. WIFI works only in my home, not at work, so I can't use this as primary OS on N900 yet.

There was couple of irritating bugs in task switcher; one was that thumbnails didn't center on screen properly and worse one was I often had to be very precise in hitting it in the right spot to activate the application.

Edit: Virtual keyboard was pain in previous builds, as it always jumped in front of terminal screen, and there were also focus errors in terminal. Now this is fixed and terminal can be used as it should. Also virtual keyboard has started to resemble Harmattan one (as it should too )