Sorry if I"m necroposting, LOL. I have an Adam that has a Pixel Qi screen that I bought second (maybe third) hand, and I use it mainly as an e-reader. I find it to be quite satisfactory. But this is the only Android tablet I've owned, so I really can't compare it with anything else.
I specially like the Pixel Qi screen, which is usable outside in the sunlight. Also, with the Adobe Reader for Android (which is free btw) I can annotate pdfs, and when I transfer it to the computer, they'll still be there. Also there are many Android apps that one can play around with.
One thing I don't like is the battery life. I have to typically charge it once or twice a day, which is annoying. I've never owned a dedicated e-reader with e-ink display, but I hear they are significantly better in this department. Also the battery is not replaceable. If it ever goes bad, it looks like I'll have to disassemble the device and replace the battery cells: that is, if I can even find the correct type of battery cell in the first place.
Many people were excited about this device, but it looks like they were disappointed when it came out, because of some promised features which were not delivered (replaceable battery, a trackpad etc.) and some initial bugs in the Android ROMs. Some people also didn't like the resolution and the color of the Pixel Qi displays (to me this is not a problem because ability to read it in sunlight make that up for me. Watching HD videos is not what I bought it for). The bugs seem to have been worked out now, and there are several different versions of Android ROMs available for this device.
Notion Ink was talking about releasing an Adam II tablet, with a TI OMAP processor which has an open architecture as opposed to the Nvidia Tegra processor used in Adam I. I don't know much about computer hardware, but I guess this means that porting of Meego or the new Ubuntu Tablet operating systems into Adam II by the respective developer communities might have been possible. The stock release was going to be Android. I have a Nokia N900 phone which has a TI OMAP processor, and I know that some people were running Ubuntu on it (command line only though). Adam II was scheduled to be released in December 2012, but I haven't heard any news lately. The blogs by the developers don't have anything new in a long time, and the official forums seem to have frozen. So maybe Notion Ink went bankrupt, or decided that Adam II is not profitable and decided to pocket the cash and disappear.