I just got one today as a Christmas gift. I like it a lot, although page turning is awkward 1 handed. The size is excellent for a hand-held device, with a large, clear screen, and a good sized virtual keyboard. I've had no problems with the Kindle App, and I loaded Mantano and tried it briefly. Oddly enough, the only problem I've had with it is a tendency to hold it upside down when looking for the power-on button.
The Samsung logo goes at the top. It is more distraction prone than my Kindle. The fast access to the network causes that. Since that was one thing I wanted it for, that's a feature, not a bug.