I have been really pleased with Windows 8 RP on my Lenovo W520, I have had no major problems. I have seen the issues with slow start-up of networking after a sleep as others have seen, but nothing else.
However today I tried to do a Lync audio call with Lync 2013 Beta and found I had no audio. Up to now I had just used the drivers Windows 8 installed which had seemed OK. It turns out I had to install the Conexant Audio Software 126.96.36.199 from the Lenovo site. Once I did this and Lync was restarted the audio leapt into life. As I remember I had a similar issue with Windows 7 and getting the audio to work correctly on my Lenovo base station.
Top tip: use the up to date drivers