Now that I had chance to play around with the new geek toy, here are my impressions:

• Connecting to WLAN is a matter of two clicks. That's plug'n play! :)
• The screen is incredibly sharp and has a 800x480 widescreen on the area of two matchboxes. The contrast is great and you can actually use the device in bright sunlight, where most LCDs fail horribly!
• The stylus is a simple piece of plastic, yet it is a good pen for clear handwriting. This makes the handwriting recognition actually useful, after you got used to it. You can write several words at once and the device tries to guess the characters. The more you practise a clear handwriting, the less mistakes the Nokia makes. If you spot a mistake, just write over the wrongly recognized letter again to correct it. That way you can even insert spaces or delete characters by crossing them out. However, the writing area is limited and only fits two or three words at once. Because of ambiguities you have to manually switch between alphanumerical and special characters modes. If your handwriting doesn't fit the predefined rules, you can teach the device your own rules.
• Controlling the device with the stylus is comfortable but some of the hardware buttons (especially the cursor keys) are awkward to use. They are bad for controlling action games.
• Without zooming in, websites are readable, but most often damn tiny. The Opera browser can either zoom the whole contents (excluding flashs), or just increase the size of characters while still horinzontally fitting the page on screen.
• The browser can only display latin and cyrillic characters. It's currently useless for browsing Asian websites.
• The device seriously lacks RAM and the software isn't rock stable. I saw the desktop hang or crash rather often. Nokia definitely has to work on this! The system also seems to leak memory.
• The speaker is tiny but has a good quality for its size. It sounds better than the speakers of my current laptop. Together with a comfortable "just-works" internet radio "desklet" (yes, the N770 desktop comes with some desktop applets) the device is good for radio streams. Earphones can be connected as well.
• Although the audio player uses gstreamer, it cannot play OGG Vorbis. :(
• I have installed a X terminal and can now explore the filesystem. Rumour had it that the root password was "rootme" but that doesn't work on my device. I guess I have to learn to build .debs to replace "/etc/sudoers" with no-password sudo access for the user.
• I wish the device had a SSH daemon. Using the shell with the on-screen keyboard isn't much fun.
• Battery life is rather short. Especially if you are connected to the net. But putting the protective case over the screen, the device automatically goes into standby mode from which it recovers in less than a second. Nokia states that the battery lasts 7 days in standby mode.
• The applications included are: audio-player, video-player (Helix-based, sometimes states that the file format of the bundled IceAge2 trailer is unsupported, but can play it if you click on play again), RSS news reader, photo viewer (awkward to use), PDF reader (not tested yet), file manager (simple but functional), control center, calculator, world time clock, notepad (for writing simple texts), paint program (comparable to MS paint on diet, but actually useful with the stylus), games (chess, solitary mahjong, a sokoban clone), a search tool for finding your files, a slow help browser comparable to yelp, Opera web browser, a tiny email tool with address book for sending and receiving mails, desktop applets (internet radio, clock, rss reader, quick internet access (simply opens www.nokia.com).

Apparently the device isn't a good replacement for a PDA or a tablet PC, but it does work well for the task it was designed for: browsing the web and sending/receiving emails at public WLAN hotspots (or anywhere else, if paired with a bluetooth-capable cell phone). It yet has to be found out for what else it can be useful, though. :)