I used to own a N810 and I sold it over 6 months ago. Now I am reading review about the N900 with interest.

I think there must be other people like me here who are previous users, but who are considering or using the N900 already. What do you think about the device in comparison to your previous Nokia tablet?

Some posts I've read here suggested Nokia 770/N8x0 users were scared away from hordes of new N900 users. But I don't see how this can be true, because the same geeks who liked the previous also are looking at the N900 too! like me.

the n900 is a different device really. on the one hand, it's so much more powerful and fun to use. on the other hand, the smaller screen does make a difference when watching videos or surfing. i still prefer my n8x0 for this. another thing is the user interface. in an attempt to copy apple, they tried to make it "simple", which of course means: less control, less options. typing on the onscreen keyboard is a PITA compared to the n8x0, because they changed its behavior, too.

overall, while the n900 is a cool device and i like it, depending on personal preferences people may feel they're better off with their old n8x0/770 tablets and will therefore not buy the n900.

I still have my 770 and N810 and they just don't get used much any more.

The on-screen keyboard may be a PITA but I wouldn't know as I've never used it - the N900 has a perfectly usable hardware keyboard. Even though it is smaller, the N900 keyboard feels easier to use than the N810's.
Sure the N810 has a bigger screen but that made it bulky and meant it didn't travel too much. The N900 goes everywhere with me - much more useful IMO.
The only thing I miss is the hardware button to toggle fullscreen mode for an application.

Had N770, N800 and N810, N800 and N810 were decent and nice to use.

But N900 gets used much more because it's in my pocket all the time!

I have an N800 N810 and N900. I still use all three, but the earlier two mainly for reading books. The N900 is much faster and more flexible. I just don't have the patience for the others in general.

Too bad, because I prefer the older form factor and would actually like bigger still.

I used to read books on my N810. If you do so often, I strongly recommend you invest in a proper e-book reader with an e-ink screen - they are much easier on the eyes.
Find a shop that stocks some and try one out, you will notice the difference immediately.

I have used my N810 an half year, then the display break. So i had to wait 3 months for my N900. I never had a direkt comparison but in my opinion,the N900 is an faster an more powerful N810 with better multitasking (i like animations). I have no problems with the smaller display size.
The features like fm transceiver and ir-transmitter makes it perfekt.
And more users brings more developers

I have a N810 now a N900

I have the 4 of them and the last has always been the best
I keep the N810 in the car for Navigation (N900 is not very good at that yet I think) and it got a new battery for that purpose.
I tried Mer on the 770 but I don't see that going anywhere (not enough power ...)
N800 is used for debugging and testing Diablo version of PWSafe
And the N900 is always in my pocket and ready to use

I have all four 770, n800, n810, n900...
The n800 is my media machine for flights/etc -- 32 GB + 16 GB SD cards: books, movies, music.
The n810 is still used mostly bedside for browsing.
The 770 is gathering dust while I try to find the time to create some "project" with it...

I wasn't going to go for the n900 because (from the chatter) it seemed that it would be abandoned like the 770...
I finally went for the n900 back in early Jan. I decided that it would likely be the last really open maemo device, so I figured that I would get one...

It is nice not having to tether to my phone (and only carry one device around). Since I used my NITs with a dumb-phone, the n900 isn't much different than my old setup. Those expecting the n900 to be a smart phone tend to be disappointed -- it is more of a smart device with a phone application.

As mentioned by others, the smaller screen can make browsing/etc a little more hard on the eyes. The camera is pretty good (I needed a new point-n-shoot camera, so the n900 filled that niche for me). The software environment is just starting to pick-up -- most of the apps from the n8x0 line are finding their way on to the n900 and there are a few glimmers of new things coming down the pipe (there is a neat demo of a panoramic photo app that was just released and games like Angry Birds)

Also, as mentioned by others, the system doesn't have quite as many options and they took away stuff like red-pill mode in the app installer because all the new maemo users were doing not-too-smart-stuff and ended up messing up their systems.

I do find the new users a bit off-putting -- they seem loud and obnoxious and seem to not want to search for answers/etc.

Would I still buy the n900? Yes, I really like it, but I am not your average consumer... I like things that present a challenge and learning opportunities. I don't like doing things the easy way.