I just installed Parallels 7 this weekend (new/full, not upgrade) on Lion on a new Macbook Air and the freeze after sleep issue immediately appeared for me. I've never experienced a resume from sleep lock up until now, which is happening happening daily. Of course I only notice it if the W7 VM session is running, but it does freeze even when if I haven't started any apps (system and backup processes excluded from that statement). I'll keep looking for a root cause, when I'm not using my computer for the reasons I actually purchased it for... like, work. Unfortunately, I really need both platforms and it's a pain to have two machines.
I've run Parallels 4, 5, & 6 on my other Macs and have similar annoying and buggy performance issues over the years that always (reluctantly) forced me to keep another Windows box on hand for work. Other than the freeze ups, Parallels 7 has been an enormous improvement in my experience, so I'm reasonably optimistic that this might be resolved.