I'm close to pulling the trigger on one. From what I've heard the problems are:
- no gapless audio (eg, if you listen to a live album there will be a gap of a few seconds between songs)
- takes 15 seconds to boot up
- there was a 24fps bug, but its been fixed with firmware
There might be other bits and pieces wrong, but they are the most annoying issues I've heard about.
The 828 and 929 have been announced so I'm hoping the price of the 818 drops...