Wow what a build up to the release of this phone. I was so excited after seeing this online at the Nokia convention in Germany. It seemed like finally someone was taking note of what users wanted in relation to multitasking. And this phone does it extremely well. You can have some of the phones applications running in the background which is great. It's what's missing from the Apple iphone. The only issue I have with this on my Nokia N900 is the battery. If you keep these apps running the battery won't last long. Be prepared to charge it every night and even take a charger with you should you have a heavy use day.
The only other criticism I'd have of this phone is that there aren't enough apps for you to take full advantage of the maemo linux operating system. I guess that will come with time.
However if you want a powerful phone in your pocket which could really be dubbed 'a mini desktop' then this is the phone for you. The controls are very intuitive and as it's a Nokia you'll find yourself burning around the phone in no time. Web browsing is better than what you've come to expect on other smart phones. The web browser is powered by Mozilla and you'll find that you can pretty much throw anything at it.
I would recommend this beast to anyone. Just save up your money first as it costs an arm and a leg. Or just wait and see if one of the networks pick it up and subsidise it.