I've got the Kindle Fire HD 7" and text rendering is better on it than on my iPad3. The iPad3 might have slightly crisper text, though that is difficult to see for certain, but overall, text rendered on the Fire HD 7" is darker and more readable thus causing less eye strain. Well for my eyes it is. So my Kindle Fire HD 7" makes an excellent LCD eBook reader.
Unfortunately, that is where my praise ends for the Fire HD. The interface is truly beyond sucky, and having to find workarounds for apps that require root access is a royal PITA. I'm not a big fan of Android to begin with, but Amazon's tweaked, limited version of Android is especially sucky. I think a lot of first time Kindle Fire HD 7" and 8.9" owners will soon learn this after receiving their units. For people who are perfectly happy to live totally within the Amazon Cloud, then these tablets are pretty darn good. For those wishing to live beyond the Amazon Cloud I think there will be disappointment.
I knew the limitations well before I bought my Fire HD and I bought it for one thing only, reading books. In my case, it is well worth the price for that function alone.