My first impressions on the HD6 is that it's tiny!
You know how I have very small child size hands well I can hold this tablet with one hand. The weight seem distributed perfectly so it's not too light or too heavy. The PPI is excellent. On the HD 7.2 it seems text is a bit fuzzy but the HD6 does not have this problem. That extra PPI really makes a difference. I think it will be excellent reading device for those who do not need gigantic text size to read on. I will agree to others this tablet is super shiny. Meaning reflections everywhere! It's super glossy so it shows finger prints quite badly. Keep a cleaning cloth nearby. The sound is good enough for audio books but sounds muffled on music. you will need additional speaker or headphones. I have not tried video on it. It's quite loud for a little device though.
One thing I notice from a regular Kindle is this tablet is narrow so the amount of text you get is smaller than a Kindle PW but due to the text rendering you will be able to easily read at a smaller text size. The text is sharp, clear and easy to see at smaller points. This is a huge plus most smaller devices skimp on this but Amazon did their homework here.
The only two cons I have found is the glossiness of the tablet which is really annoying and the speaker quality. Once I get a case the quality will probably sound better in my experience with Poetic cases.
The back is plastic so if you read normally without a case you want to get a TPU case to give some grip to it.