So far I don't see any perf issues with the rig I am running (older i5, 4GB RAM, Intel GPU 1TB HD). However I do see issues with the entire start menu feature. That is so buggy and full of UI consistencies I feel that they are going to shoot themselves in the foot with OEMs and power users.
Since most power users know not to install any MS OS that has not seen the "SP1" update and OEMs are not willing to take a bath like Win8 MS needs to release a "it just works" version.
Also its possible that the idea of the "free" version makes early adopters the final bug testers. I know that I will be waiting till the last possible moment to get the free version installed unless it looks like things work pretty good from the get go.