It is sold as a mobile computer with the Internet in its heart, and it was introduced as 'step 4 of 5' for tech leaders / lovers. If you want a mature Nokia mobile phone with extensive Java support and full SIM features then there are plenty of choices based on Series40 and Symbian. I think Nokia has been clear on that since http://maemo.nokia.com was launched this Summer.

The N900 is the best mobile device I have ever got. I'm really happy with it, using it at all times. I have met plenty of very interesting people with the income and the chance to buy whatever high-end device, and they had an N900.

Others might have different opinions, of course.