I have used my Nexus 7 for about 3 days and find some issues with internal speakers. The sound is a bit tinny and volume is also not especially loud while I am playing youtube videos. If I change the speaker at higher levels, sounds become fuzzy and distort. But my PLayBook have full stereo sound. It seems to be a loudness issue. Using a speaker boosting app helps me a little.
When the volume is completely muted or turn the screen off, the speakers are still crackling at random, even disabled sound in the settings. Sometime it stops working and I have to get it back by reboot tablet.
Hope Google quickly releases a software update to fix the issues.