I had an Archos 101 briefly before returning it (10" android tablet...pretty nice one, actually). I returned it after realizing between my Evo 4G smartphone (4" ish android phone) and my Duo, it was completely redundant.
Here's my general opinion of tablets vs. netbooks/laptops:
If all you want to do is browse information or data (surf the web, read emails, play simple games, view pictures/videos, read ebooks, etc), then a tablet is a perfect piece of hardware. It's portable, great battery life, and fast, if you get a nice one. It's also simple to use...so there's virtually no learnign curve if you're not technologically savvy.
But if any part of your computer use involves MANIPULATING information or data (writing long emails, using MS Word, using powerpoint, any sort of programming, lots of typing, altering photos, editing pretty much anything, etc), then you NEED a PC. It's more versatile, more customizable, and allows faster input of information. The Duo provides a great- well, to use their word- HYBRID experience. It's not a powerful piece of hardware per say (you won't be doing complex engineering and graphic design on it like a powerful desktop), but its form factor allows a lot of input and manipulation. And in tablet mode, it provides basically the same advantages as the tablet with the exceptions of size and battery life.
For a sort of microcosm example....typing this post would be about the extent of the data manipulation I would do on a tablet without becoming frustrated, and it's not even a particularly large block of text. If I do this or more involved things often, I want a physical keyboard and a trackpad or mouse. If all I'm planning to do is read other people's posts and occassionally write a few lines in return, that's a tablet's sweet spot.