Incredible with a bit of work
If you're the technical type of person, this thing is amazing. You can get it to do just about anything to an extent. It's a low-resource environment, so HD video and graphically intense games aren't really an option, but that's basically it. Especially now, a years after it's release, it's really developed.

Canola, one of media players available for the n800, puts the iPod to shame, it covers media in either SD card slot, including music, playlists, radio streams, videos, and images. It also has a plugin for the built in FM radio.

There are several games available besides the ones included in the preinstalled software, things like Quake 2, Metal Blob Solid, and Beneath a Steel Sky.

Did I mention that it's hackable? Linux gurus are in a familiar environment, you can use tools you use every day or install your own. Compiling for it is a bit tricky, but you typically find binary packages now anyway. The 256mb of flash memory is limiting, yes, until you have it booting from a nice big SD card. If you like to have a device be thoroughly personalized on a technical level, this is like a dream. If there isn't already a book about hacking the n800, one could rather easily be written. It's a whole lot cheaper than most devices that fill the same function, and a great place to start with this type of tinkering.

Basically, it's a hacking toy, and not for the casual user. You can make it just about whatever you want, but it takes a bit of work to get it perfected for it.

Cool gadget! I wish it had more power...
I find the N800 to be an awesome toy! I've tried to use it a couple of times as a replacement for a computer, but have gotten tired of it very quickly.
The small screen is inadequate for feature-crowded sites like amazon or facebook... one has to pan around to much. Furthermore, when I bought it I expected more performance out of the browser... I just find it a little too slow, and hard to work with if you like tabs (who doesn't nowadays).
It does however work quite nicely for watching youtube videos and other non-HD content.
Since Maemo is an open platform, you have access to millions of applications. The N800 can become a fancy MP3 player, movie player, handheld game device, etc...
It is not a cellphone! Nor does it need to be one.

Great Micro Internet Tablet
I first viewed this product in a computer store in Copenhagen in the spring of 2007 and had to have one. As soon as I got back to the states I started bugging the folks at Best Buy and Fry's and finally got one from Fry's. These things, once they hit the market,literally flew off the shelves. Up until this last year I was a total road warrior, working for a major computer company and I had this unit with me all the time. I had trained on other larger touch screen tablets, so working with this one was a breeze. The screen has incredible resolution and I love it. The software support and especially the 2008 upgrade was great. The only real issue that I have had is that this unit does not support the SDHC chips, so you are limited in the amount of data that you have onboard at any given time, however, I carry a small case with a full load of the 2 G chips. Works great for either music or video too.
The one caution that I would make and I found this out the hard way is that the touch screen is somewhat sensitive and if you carry it in your pants pocket in the provided soft sleeve, it will have problems and need to be replaced. Mine spazed out and I had to send it in. Cost about 5 to fix. Bottom line, get a hardcase, which I should have known better and done from the beginning.

Fun but underpowered
I highly recommend this product if you don't own an ultra portable laptop and don't plan on buying one. If you plan on getting a portable laptop that you wont mind carrying everywhere then you will find yourself using your N800 less and less. When I originally bought the N800 I didn't have a portable laptop and by portable I mean less than 5 pounds so using the N800 was great to check my email and surf the web in my down time. That being said the major problem I found was that the processor really cant handle too many apps running at one time, also the internet is really bogged down when experienced through the N800. Even though the Nokia site advertises it as full video experience loading videos and getting them to play on the flash player installed can be really slow when the videos actually play. All that aside if you want to use it for minimal surfing or entertainment on a long ride or flight then it is perfect because it does have the ability to play saved videos, music and games just as long as you don't try to get the N800 as opposed to a laptop even with the bluetooth keyboard; which I also have.

Nearly All-In-One Note Keeper
I've always kept lots of notes for shopping lists, to-do lists, appointment reminders and so forth, but it was hard to keep track of these notes and to keep them up-to-date. So, I was looking for a device which would allow me to keep all such notes in one place. The Nokia N800 Internet Tablet pretty much allows me to satisfy all these needs. And, it also: will display photos, videos, music & e-books; has wi-fi internet access, an appointment calendar, a contact list, a calculator & games; uses a Linux os with much user support.

Unfortunately, this model has been discontinued after being replaced by the N810. Personally I don't need the GPS or built-in keyboard of the N810. I prefer the use of 2 full-sized SDHC cards, virtual keyboard and built-in FM radio which the N800 has.

I bought one of the last 2 N800s available from Amazon which was described as "used, like new". Upon receipt, I discovered it was missing the charger. However, Amazon gave me a credit which more than compensated for the cost of a new Nokia charger. I also encountered a performance problem, but this was covered by the Nokia warranty.

I'm very satisfied with Amazon and with the N800. I just hope it doesn't die because I'm not as convinced the N810 is as worthwhile given its relatively higher price. I'm optomistic the N800 will last well beyond the production lifetime of the N810.