Sounds to me like you're getting what you pay for... an underperforming tablet that pushes you to join or use Prime.
Seems like if you keep your expectations in line and/or can leverage Prime for all it's worth, it's a decent device. If you expect it to run as fast as a full-fledged tablet, you will be disappointed.
I'm not sure if I should be surprised that the first iteration is a little off.
The Kindle 1 never caught my fancy, but that was also a much lower profile device / launch.