Here is some answeres for what you are experiencing:
1. When switching from scart to HDMI (1) the sound is still coming from scart, not from HDMI (1) when no audio is send by HDMI device.
2. Much apps don't exit by using the back button, they stay running for example, uitzending gemist (by pressing red button), videoland and youtube apps do this.
3. User interface is a little slow in my opinion, it's not responding very fast and doesn't smoothly scroll
4. The blue bar which is shown then waiting and going from left to right and back for a while has a blue glow, but this blue glow is cut off by the box (it's not nicely fading out, but cut off at 25% density or somewhat)
5. Ambilight can't stay on in stand-by mode, when pressing the ambilight button the ambilight setting is changed (of, dynamic, static) while screen is off.
Please see the following link regarding this.
6. When playing from a DLNA source audio is sometimes not supported
Please check the supported audio codecs for the different extensions files, found in the User manual under Multimedia.
7. Audio stops for 500 ms a few times a minute and continues when using multi channel audio output over spdif
Have you tried any other audio output? If so, which ones and what is the result of this?